1. First generation 1960–1966
    Medium- & heavy-duty models 

2. Second generation 1967–1972
    Engines  Trim Levels (Chevrolet)  Trim Levels (GMC) 

3. Third generation 1973–1987
    Interior and safety  Chassis and powertrain  Engines  1981 mid-life cycle facelift  R/V-Series  Sidesaddle fuel tank controversy  Foreign production 

4. Fourth generation 1988–2000 (GMT400)
     1999 models   C/K in Oceania  Engines^[73]  Sport Equipment Package (RPO code BYP) ^[74]  454SS (RPO code B4U)  C3500 HD  Engines 1991–2000  Engines 2001–2002  Wheels 

5. Brazilian versions

6. See also

7. References

8. External links

The C/K was Chevrolet and full-size pickup truck line from October 1959 until 2000 in the United States and Canada, from 1964 to 2001 in Brazil, and from 1975 to 1982 in Chile. From 1959 to 1987, C/K was also the name of GMC's truck series; it switched to the name Sierra from 1988 to 1999 while sharing the C/K platform. The first Chevrolet pickup truck was introduced in 1924, though in-house designs did not appear until 1930. "C" indicated two-wheel drive and "K" indicated four-wheel drive. The aging C/K light-duty pickup truck was replaced with the Chevrolet Silverado and GMC Sierra names in 1999 in the United States and Canada, and 2001 in Brazil; the Chevrolet Silverado HD and GMC Sierra HD heavy-duty pickup trucks followed. Until this time, the names Silverado and Sierra were used to identify the trim level of the C/K trucks.

For the first Chevrolet C Series, made from 1911 to 1913, see Chevrolet Series C Classic Six (the first Chevy).

First generation 1960–1966

Launched in the fall of 1959, the 1960 model year introduced a new body style of light pick-up truck that featured many firsts. Most important of these were a drop-center ladder frame, allowing the cab to sit lower, and independent front suspension, giving an almost car-like ride in a truck. Also new for 1960 was a new designation system for trucks made by GM. Gone were the 3100, 3200, and 3600 designations for short 1/2, long 1/2 and 3/4-ton models. Instead, a new scheme assigned a 10, 20, or 30 for 1/2, 3/4, and 1-ton models. Since 1957, trucks were available from the factory as four-wheel drive, and the new class scheme would make this known. A C (conventional) in front of the series number designates 2-wheel rear drive while a K designates 4-wheel drive.

Actual badging on Chevrolet trucks carried the series name system from the previous generation for 1960 and 1961: the 10, 20, 30, and 40 series (C and K) were badged as "Apaches", 50 and 60 series trucks were badged as "Vikings", and the largest 70 and 80 series models were marked "Spartans". For 1960, C/K trucks were available in smooth "Fleetside" or fendered "Stepside" versions. GMC called these "Wide-Side" and "Fenderside". Half-ton models were the C10 and K10 long-bed and short-bed trucks, and The 3/4-ton C20 and K20, as well as the one-ton C30, were also available. GMC did not use the "C" nomenclature, though their 4x4 versions used the "K" nomenclature. GMC model numbers for 1/2, 3/4, 1, and 1.5 ton were 1000, 1500, 2500, and 3000. The 1.5 ton Chevrolet C40 and GMC 3000, which were using the light-duty cab^[4][5] (but only as chassis-cab and stake models), were discontinued for the 1963 model year.^[5][6]

The 1960, 1961, and 1962 models featured torsion bar front suspensions, with trailing arm suspension rears. Trim lines were base and "Custom". Engines included the base GMC 305 in³ V6 for the GMC version, 135 hp (101 kW) 236 in³ (3.9 L) and 150 hp (112 kW) 261 in³ (4.3 L) straight-6s, and a 283 in³ (4.6 L) V8 with 185 hp (119 kW).

A coil-spring front suspension came in 1963, along with a new base engine, a 140 hp (104 kW) 230 in³ (3.8 L) I6, and an optional 165 hp (123 kW) 292 in³ (4.8 L) I6. The cab was modified for 1964, with elimination of the "wraparound" windshield and a new front grille design, along with various interior changes, while retaining the original design on the body. Air conditioning and a 220 hp (164 kW) 327 in³ (5.3 L) V8 came in 1965. A new base engine finished the model in 1966 with a 155 hp (116 kW) 250 in³ (4.1 L) I6.

Medium- & heavy-duty models

Medium-duty trucks were:

• 1½-ton Chevrolet C40 / GMC 3000 (1960–62), with the light-duty cab;
• Chevrolet C50 and C60;
• GMC 3500, 4000 and 5000.

Heavy-duty trucks were:

• Chevrolet C60-H^[7] (a C60 with a heavier GVWR: 22,000 lbs instead of 19,500 lbs), C70 (1960–61) and C80;
• Chevrolet tandem rear axle models M60 (1963–66), M70 (1960–61) and M80 (1962–66);
• GMC 5500, 6000 and 6500;
• GMC tandem rear axle models W5000, W5500 and W6500.

Second generation 1967–1972

A new, more modern look came for 1967, along with a new nickname: "Action Line". It was with this revision of the C/K truck that General Motors began to add comfort and convenience items to a vehicle line that had previously been for work purposes alone. The majority of 10 series and some 20 series Chevrolet trucks from 1966 to 1972 were equipped with a coil spring trailing arm rear suspension, which greatly improved the ride over traditional leaf springs. However, the leaf spring rear suspension was still available on those trucks, and standard on 30 series trucks. GMC-branded trucks came standard with leaf springs in the rear, with the coil spring/trailing arm design optional. All 2-wheel drive trucks came with independent front suspension, while 4x4's used a conventional solid axle with leaf springs. 1967 was the only model year for the "small rear window" (RPO A10 offered a large rear window as a factory option^[8]). The standard drivetrain was a three-speed manual transmission and one of two engines; the 250 in³ straight six or the {{convert|283|cuin|L|1|abbr=on}} V8. Optional transmissions included a three speed overdrive unit (C-10 only) and several different four-speed manuals, the Powerglide 2-speed automatic, or the Turbo-Hydramatic 350 and 400 3-speed automatic.The 292 six and the 327 in³ V8 were optional engines. 10-series trucks came with a 6 x 5.5–inch bolt pattern, the 3/4 and 1 ton trucks came with an 8 x 6.5–inch bolt pattern.

The most visible change in differentiating a 1968 from 1967 models was the addition of side-marker reflectors on all fenders. Also, the small rear window cab was no longer available (the C40 and C60 medium duty trucks retained the small window). The GMC grille was revised, with the letters "GMC" no longer embossed in the horizontal crossbar. Another addition was the Custom Comfort and Convenience interior package that fell between the Standard cab and CST cab options. In 1968, Chevrolet celebrated 50 years of manufacturing trucks, and to commemorate, they released a 50th Anniversary package featuring an exclusive white-gold-white paint scheme. Also in 1968, the 307 and 396 CID V8's were added as well as the Longhorn model on 3/4 ton trucks. Featuring a 133-inch wheelbase, the Longhorn added an extra {{convert|6|in|cm|abbr=out}} to the bed. Longhorns were only two-wheel-drive; no factory Longhorn 4x4 was built.

The 327 c.i. V-8 engine (220-240 gross HP in '67-8) was dropped in 1969 in favor of the 350 CID variant rated at 255 gross HP (200 net H.P. or 195 net H.P. with "A.I.R." smog equipment). Along with the new engines came a new grille design for Chevrolet trucks and a more upright hood for both Chevrolet and GMC trucks. A utility variant, known as the K5 Blazer, was also introduced with a shorter wheelbase of {{convert|104|in|mm|0}}. The GMC version, known as the Jimmy, was introduced the same year. Some internal cab changes were also made, most notably the switch from a hand-operated parking brake to a foot pedal, and a more modern looking two-spoke steering wheel with plastic horn button replaced the previous year's three-spoke wheel with chrome horn button. Also new this year were upper and lower side moldings, which added another two-tone paint option. These were standard on CST trucks, and optional in any other trim level. The Sierra and Sierra Grande option packages were also added for GMCs; these were to become discrete trim levels in 1972.

The only noticeable change for 1970 was a minor update to the Chevrolet grille. At first glance, the 1969 and 1970 grilles look very similar. However, the 1970s plastic inserts actually have highlights that divide the appearance into six separate sections. The 396, while still sold as such, was enlarged to 402 cubic inches starting in 1970.

Numerous changes occurred in 1971. First came another new grille design (the "egg crate") for Chevrolet trucks and black paint over portions of the GMC grille. Second, an additional trim package was introduced: the Cheyenne. On GMC models, this was equivalent to the Sierra. These packages consisted mostly of comfort features — nicer interiors, more padding and insulation, carpet, chrome trim, and upper and lower side molding and tailgate trim. 1971 was the first year for AM/FM radios factory installed. Finally, the front brakes on all light-duty trucks were switched from drum brakes to disc brakes, resulting in much less brake fade under heavy use. A divot and adjustment screw was added to the inside of the door located above the door panel and near the vent window. The screw provided a way to adjust the gap in the window track. This change was made due to the window track loosening over time. While prior C/K half-ton trucks had used a six-lug bolt pattern (6 x 5.5") for the wheels, two-wheel-drive models switched to a five-lug pattern (5 x 5–inch bolt circle) common to Buick, Oldsmobile, Pontiac, and Cadillac passenger cars. The 1/2 ton 4 x 4 retained the 6 lug bolt pattern. This bolt pattern would remain the standard through the end of the C/K series (along with the Chevrolet/GMC vans). The 20 and 30-series trucks had the 8 x 6.5" pattern. Also, Chevrolet changed the 396 V8 emblem designation to 400 V8.

The 1972 models were very similar to the 1971 models, with the only change being the rear view mirror was glued to the windshield rather than bolted to top of the cab, and metal or vinyl-covered flat door panels were no longer available; all trim level door panels were molded plastic with integral armrests and wood grain inserts on Cheyenne and Sierra trim levels. For restoration, it should also be noted that the door and window cranks were slightly longer due to the molded plastic door panels, and the vent windows were now secured with a single screw on the inside of the door, thus differentiating it from the 1971 model year. The trim levels were rearranged on GMCs, with the Custom now being the lowest level (the Deluxe being dropped) and the Sierra and Sierra Grande becoming separate trim levels at the top of the lineup rather than option packages as before.

Engines

Trim Levels (Chevrolet)

A 10, 20, or 30 on the emblem indicates {{frac|1|2}}-, {{frac|3|4}}-, or 1-ton trucks. There are also 40- to 80-series medium- and heavy-duty trucks:

• medium-duty
  • {{frac|1|1|2}}-ton C40;
  • "light" 2-ton C50;
  • 2-ton C60;
• heavy-duty
  • "light" {{frac|2|1|2}}-ton C70;
  • {{frac|2|1|2}}-ton C80.^[13]

These models share the cabin of the light-duty models but sit on a taller chassis and have a taller front end of a different design, with a clamshell hood.

Trim Levels (GMC)

1500, 2500, and 3500 designations were used to indicate {{frac|1|2}}-, {{frac|3|4}}- and 1-ton trucks. Sierra and Sierra Grande had been used as names on option packages since the 1969 model year.

In both series, the 'Highlander package' included special color-coordinated houndstooth cloth inserts and additional trim colors and insulation.

Third generation 1973–1987

An all-new clean sheet redesign of General Motors' Chevrolet and GMC brand C/K-Series pickups debuted in mid-1972 for the 1973 model year. Development of the new third-generation trucks began in 1968 with vehicle components undergoing simulated testing on computers before the first prototype pickups were even built for real world testing.^[16] The redesign was revolutionary in appearance at the time, particularly the cab, departing from typical American pickup truck designs of the era. Aside from being near twins, the Chevrolet and GMC pickups looked like nothing else on the road.^[17] The third-generation trucks are colloquially known as the "Square-body" or "Box-body" generation.^{[18][19][20][21]} GM's official "Rounded-Line" moniker highlighted the pickup's rounded styling cues that were incorporated into the design. This included rounded windshield corners, rounded corners of the cab roof, rounded-corner doors which cut high into the cab roof eliminating roof height, slanted front fenders, and rounded pickup box corners which allowed for rounded wraparound taillamps, a first for GM pickups. The design also featured strong distinctive curved shoulderlines which rounded out below the beltline.^[18] The curved shoulderline continued across the back tailgate on Chevrolet Fleetside and GMC Wideside models. However, the low slope of the hood and rectangular front end of the truck originated the "square/box-body" nickname, which was propagated through truck magazines and word of mouth.

GM's design engineers fashioned the "Rounded-line" exterior in an effort to help improve aerodynamics and fuel efficiency, using wind tunnel technology to help them sculpt the body.^[22] Other design traits include sleek sculpted body work, an aerodynamic cab with steep windshield rake, and a unique available hidden radio antenna embedded into the windshield glass.^[18][23][24]

There were two types of pickup boxes to choose from. The first type, called Fleetside by Chevrolet and Wideside by GMC, was a full width pickup box and featured a flared shoulderline to complement the cab in addition to rounded box corners and the new aforementioned rounded wraparound taillamps. Both steel and wood floors were available. The second type, called Stepside by Chevrolet and Fenderside by GMC, was a narrow width pickup box featuring steps and exposed fenders with standalone tail lamps. Initially, only wood floors were available.^[25]

The wheelbase length was extended to 117.5 in (2,985 mm) for the short wheelbase pickups, and 131.5 in (3,340 mm) for the long wheelbase pickups. A new dual rear wheel option called "Big Dooley" was introduced on one-ton pickups, along with a new Crew Cab option on the {{convert|164.5|in|mm|0|abbr=on}} wheelbase. An optional Elimipitch camper was made available for the Big Dooley.^[26] Crew Cabs were available on C30 pickup and chassis cab, and K20 chassis cab models in two versions: a "3+3" which seated up to six occupants and "bonus cab" which deleted the rear seat and added rear lockable storage in its place. The fuel tank was moved from the cab to the outside of the frame, and a dual tank option was available which brought fuel capacity to 40 US gallons. 1980 was the first year that a cassette tape player could be purchased, along with a CB radio.^[27]

The Rounded-Line generation ultimately ran for a lengthy 15 model years (1973–1987) with the exception of the Crew Cab (C/K-30 four-door cab), Blazer, Jimmy, and Suburban versions, which continued up until the 1991 model year. GM ends this generation with 1987 as 1987 was the last model year for the conventional cabs (two-door cab).

Interior and safety

The third-generation pickups were offered in several equipment level packages or trim packages. Chevrolet/GMC used various names for the trim levels throughout the vehicle's life cycle and some were rearranged in their class order. For the 1973 and 1974 model years, the base (standard) trim level was Custom/Custom, mid-range trims were Custom Deluxe/Super Custom, luxury trims were Cheyenne/Sierra, and top-of-the-line luxury trim levels were Cheyenne Super/Sierra Grande.^[16]

For the 1975 model year the trim levels were revised and the base trims were now Custom Deluxe/Sierra, mid-range trims were Scottsdale/Sierra Grande, luxury trims were Cheyenne/High Sierra, and the top-of-the-line luxury trim levels were now known as Silverado/Sierra Classic. They remained in this configuration up to the 1987 model year.^[25] For the 1982 model year, the luxury trim levels were dropped, leaving the base, midrange, and top-of-the-line luxury trim level packages.^[28]

Soft touch materials were used throughout the passenger cabin, such as the dashboard, doors (arm rests), steering wheel, and shift levers. Subtle grained interior panels and bright metal work was used on the inside with high-quality materials also used on the outside, like chrome, aluminium, and polished stainless steel, particularly on top-of-the-line luxury Silverado or Sierra Classic trim levels. Custom Vinyl vinyl or soft Custom Cloth cloth and velour seating surfaces were used along with fabric headliners, door inserts, and plush carpeting, depending on the trim level. Upper class trim levels also used acoustic deadening materials for quieter ride comfort.^[29] From model years 1973 to 1977, chestnut wood grain inserts were used on the dashboard and doors for further visual enhancement. The wood grain inserts were replaced by bright brushed aluminium inserts for model years 1978 to 1987.^[30] A Delco AM/FM audio sound system and an all-season climate control system that heated, cooled, cleaned, and dehumidified were optional extras.^[31]

At its launch in 1972, the Square-body C/K-Series introduced two firsts in safety advancements concerning full-size pickups, and would later lead a third safety advancement in 1975. The first was the standard passenger-side sideview mirror, and the second was the energy-absorbing collapsible steering column. Patented by GM and already in use in its cars since 1967, the new energy-absorbing steering column was standard on all C-Series and K-Series models.^[16][32][33]

The third safety advancement was the introduction of dual front lap-and-shoulder safety belts with emergency locking retractors for outboard occupants in 1975 for the 1976 model year.^[34] These replaced the outdated and inadequate lap belts previously used. A center lap safety belt with slack adjustment was provided for the center occupant. Ford and Dodge would follow one model year later adding lap-and-shoulder safety belts to their pickups.^[35][36]

Other safety features included soft-padded interior panels for appearance and safety, 3,329 square inches of tempered and laminated safety glass, prismatic rearview mirror, six turn-signal indicator lamps with asymmetrical flash, four-way hazard function, and lane departure function.^{[16][29][37][38]}

Chassis and powertrain

Third-generation Square-body C/K-Series pickups gained an all-new, high tensile strength carbon steel ladder type frame with "drop center" design.^[23][39][40] Steering controls included variable-ratio recirculating ball steering gear with optional hydraulic power assist. Braking controls included front self-adjusting disc brakes with rear finned drum brakes and optional four-wheel hydraulic Hydra-Boost or Vacuum-Boost power assist.^[16] Engines choices initially consisted of six or eight cylinder engines with either manual or Turbo Hydra-Matic transmissions.^[16]

C-Series pickups included two-wheel drive and featured an independent front suspension (IFS) system with contoured lower control "A" arms and coil springs. GM's new Load Control rear suspension system took up residence in the back. The Load Control rear suspension system consisted of a rear live axle with dual stage Vari-Rate multi-leaf springs and asymmetrical (offset) shock absorber geometry, to help sort out any "wheel hop" under heavy loads or hard acceleration.^[23]

K-Series pickups included either Conventional, Permanent, or Shift-on-the-move four-wheel drive. The latter system was introduced for 1981. Regardless of the type of four-wheel drive system equipped, all K-Series pickups featured four-corner Vari-Rate multi-leaf springs, front live axle with symmetrical (inline) shock absorber geometry, and the Load Control rear suspension system. K-Series pickups also featured an off-road oriented design, with the transfer case bolted directly to the transmission and running gear tucked up as high as possible under the vehicle to reduce the chances of snagging vital components on obstacles, as well as to achieve a low silhouette and optimal ground clearance.^[41] Exposed brake lines wrapped in steel were standard, with underbody skid plate armor optional for further protection.

Conventional four-wheel drive pickups featured manual locking hubs and a two-speed New Process 205 transfer case with four drive modes: Two High, Four High, Neutral, and Four Low. Two High gave a 0:100 torque split, while Four High yielded a locked 50:50 torque split. Four Low applied reduction gearing. The front and rear propeller shafts were locked at all times in Four High and Four Low. Neutral allowed for flat towing, or use of the power take off (PTO).^[42]

Permanent four-wheel drive pickups featured a two-speed dual New Process 203 transfer case with planetary center differential and lock. Five drive modes were provided: High, Low, Neutral, High Loc, and Low Loc. In High the center differential was unlocked and allowed the front and rear propeller shafts to slip as needed for full-time operation. The system could be manually shifted into High Loc which locked the center differential for a locked 50:50 torque split. Low and Low Loc applied reduction gearing with or without lock, depending on the mode selected. Neutral was also available for use of the PTO.^[42]

A new Eaton Automatic Differential Lock (ADL) was introduced in 1973 as an optional extra on the Rounded-Line C/K-Series pickups, for the rear hypoid differential. The new automatic locking differential was offered under the G86 code, replacing the Eaton NoSpin differential, and eventually replacing the old Positraction limited-slip differential in 1974, at which point it assumed the G80 code.^[43] The Eaton ADL featured intelligent differential control via an internal governor which monitored vehicle speed and wheel slip to know when to automatically lock and could lockup 100 percent at or below 20 mph (32 km/h) increasing tractive effort. The differential lock would unlock and deactivate at speeds above 20 mph for safety reasons, such as the vehicle being on dry pavement.^[44]

Towing and payload capacity ratings for Rounded-Line C/K-Series pickups varied, depending on how they were configured. Factors such as engine and transmission combination, differential gear ratio, curb weight, and whether the pickup was two-wheel drive or four-wheel drive decided how much the pickup could safely tow or haul.

A properly equipped C-Series half-ton class pickup could tow up to 8,000 lbs (4 tons) of braked trailer, while a properly equipped C-Series three quarter-ton or one-ton class pickup could tow up to 12,000 lbs (6 tons) of braked trailer.^[45] Adding four-wheel drive reduced towing capability due to increased curb weight, which resulted from additional driveline components (transfer case, front axle, front differential, front propeller shaft, and so on) needed to facilitate four-wheel drive. A properly equipped K-Series half-ton or three quarter-ton class pickup could tow up to 6,500 lbs (3.25 tons) of braked trailer, whilst a properly equipped K-Series one-ton class pickup could tow 500 lbs more, up to 7,000 lbs (3.5 tons) of braked trailer.^[45]

Heavy-duty towing equipment was available for both C and K-Series pickups, such as the Trailering Special package (included power steering, uprated battery, and uprated generator), 7-pin trailer electrics connector, heavy-duty engine oil cooler, heavy-duty transmission oil cooler, and a weight distributing trailer hitch.^[25][46]

For the 1975 model year, the 185 hp {{convert|400|cuin|L|1|abbr=on}} small-block V-8 was added to the line and there was a realignment of Chevy trim levels, along with new grilles and clear/white instead of orange front turn signals. Base models gained a passenger-side woodgrain dash accent and a new plaid upholstery pattern (which would change slightly each year until 1978).

A new gauge to show voltage replaced the ammeter in 1976, and the engine size decals were removed from the grille during this model year.

For 1977 models, power windows and power door locks were introduced as an optional extra. There was another round of new grilles, revised inner door panels that left less metal exposed, a four-wheel drive, full one-ton chassis was added to the lineup, and a Dana 60 was used for the front axle, as well as an electric oil pressure gauge replacing the mechanical unit. Trucks with an optional trim level, but without an additional wheel upgrade, received flatter stainless steel hubcaps, still with painted accents. This was also the only year with yellow painted trim instead of black.

All models got new, flatter dash trim panels, black on the lower two trims and aluminum-look on the fancier two. Base models received the flatter stainless hubcaps, and Stepsides got new squared-off taillights with built-in backup lights and side markers, while the rear fenders were smoothed out where the old side markers were. Fuel doors were added on models equipped with a bed to hide the previously exposed fuel caps.

The 1979 models got a new grille surround that incorporated the turn signals; inside there was a new full-width "houndstooth" seat trim on base models and a (rare) fifth interior color option on the higher series called "oyster" by Chevrolet and "Mystic" by GMC (mostly white with a gray dash, carpeting and cloth). Fuel doors were added in 79 to the rest of the lineup, following the previous years change on models with a bed.

For the 1980 model year, permanent four-wheel drive was discontinued on K-Series, leaving only conventional four-wheel drive. Some pickups gained a new grille, others did not; high-trim Chevys had both a new surround that incorporated near-flush square headlights and revised turn signals with a new, squarer grille pattern, while a GMC base model was entirely carryover, base Chevys had the new center section in the 1979 surround while GMCs with uplevel trims or the separate RPO V22 option had the new square-light surround with the main grille introduced in 1977. Blue interiors were a darker shade than before.

Engines

1981 mid-life cycle facelift

A mid-life cycle cosmetic facelift and mechanical refresh was carried out for the 1981 model year. In response to the recent 1979 energy crisis, the 1981 rework featured several fuel saving techniques to help make the Rounded-Line C/K-Series pickups more fuel efficient. Again, engineers turned to wind tunnels to resculpt the front end with new sheet metal, reducing areas which could hinder air flow and cause drag.^[29][48] A sleeker front bow-like look emerged, similar to a ship's bow with the front end being gently swept back from the center. New dual tier halogen headlamps became available with the Deluxe Front Appearance package.^[29] Mechanical updates included more anti-corrosion techniques, reduced weight, and a new 5.0 L 305 cubic inch V-8 with electronic spark control. The 5.7 L 350 cubic inch pushrod V-8 was offered in California in place of the new 5.0 L 305 engine with electronic spark control, which did not meet California's emissions requirements.^[29]

A new Shift-on-the-move four-wheel drive system with two-speed dual range New Process 208 aluminium transfer case was introduced on K-Series pickups for the 1981 model year. It replaced the permanent four-wheel drive system, on pre-1980 models. The shift-on-the-move four-wheel drive system featured new automatic self locking hubs and synchronized direct high range planetary gearing, such that the truck could be shifted from two-wheel drive, to fully locked four-wheel drive at speeds of up to 25 mph.^[49] Once the shift from two-wheel drive to four-wheel drive was made, the vehicle could be driven at any forward or reverse speed. Four drive modes were offered: Two High, Four High, Neutral, and Four Low. Two High gave a 0:100 torque split, with Four High yielding a locked 50:50 torque split through direct synchronized gearing. Four Low applied reduction gearing with a 2.61:1 ratio, compared to the previous New Process 205's 1.96:1. The front and rear propeller shafts were locked at all times in Four High and Four Low. Neutral was provided for disengagement of both propeller shafts. Conventional four-wheel drive was still available with manual locking hubs.

A new four-speed Turbo Hydra-Matic 700R4 transmission with overdrive gearing became available in 1981 for the 1982 model year. The 151 hp {{convert|379|cuin|L|1|abbr=on}} Detroit Diesel V-8 was added^[50] to replace the LF9 Oldsmobile diesel. Chrome front bumpers were now standard on base models.

1985 saw the new {{convert|262|cuin|L|1|abbr=on}} LB1 (with a Rochester Quadrajet carburetor in lieu of fuel injection) introduced to replace the 250 inline six (the 292 continued in production until it was officially phased out in 1990). Hydraulic clutches were introduced. Also, a new grill was used.^[51] The most expensive radio was the AM/FM stereo seek/scan with cassette tape at $594.^[51] A variation of the C/K series was introduced in 1985 in Brazil,^[52] replacing the locally produced C10, introduced in 1964.

R/V-Series

For the 1987 model year, the last model year for the conventional cab pickups, the Rounded-Line C/K-Series were renamed the R/V-Series. R-Series now designated two-wheel drive, while V-Series represented four-wheel drive.^[53] The name change is also found in the vehicle identification number.^[54] This was done in preparation for the next generation GMT400 trucks, which were produced concurrently with the older line. The new 1988 model trucks entered production December 8, 1986 at Pontiac East, Oshawa, and the new Fort Wayne plant. The 1987 models continued to be built at Janesville, St. Louis, and Flint.^[55]

Along with the name change, came other major improvements and tweaks for the final model year of the conventional cab pickups. Single-point electronic throttle-body fuel injection (TBI) was introduced on GM's full-size pickups, with new electric fuel pumps and high-pressure fuel lines. In addition, a "smart" powertrain control module (PCM) was also introduced, which controlled the fuel injection system, fuel-to-air burn ratio, engine ignition timing, and (if equipped with an automatic transmission) the Turbo Hydra-Matic's turbine torque converter clutch.^[56] The 5.7 L 350 cubic inch pushrod V-8 was introduced to the order books for R-Series and V-Series half-ton class pickups, with the new TBI fuel injection system. Horsepower and torque output was increased to 210 hp, and 300 lb-ft of torque.^[57]

After 1987, R/V remained in use for the Rounded-Line one-ton crew cab pickups through 1991 (built at Janesville), chassis cab (which was phased out after 1989; single cabs were discontinued in the US/Canada where the production tooling was shipped to Mexico where it remained in production until 1991), and the Rounded-Line utilities (Chevrolet K5 Blazer and Suburban, built at Flint) through 1991. From the 1988 model year and onward, C/K was re-used for the fourth-generation "GMT400" design.^[58]

Sidesaddle fuel tank controversy

The third generation of GM's full-size pickup line had a fuel tank design that drew criticism after the model run ended. The fuel tank was relocated from the cab to the outboard sides of one or both frame rails beneath the cab floor extending under the leading edge of the pickup box, commonly referred to as a sidesaddle arrangement.

The writer and editorialist Walter Olson made the following points: According to a later-debunked 1993 report on Dateline NBC, this arrangement made the trucks prone to exploding in a side collision.^[59] The faked video was staged by an expert witness for hire against GM, Bruce Enz of The Institute for Safety Analysis. Enz used incendiary devices and a poorly fitted gas cap to create the impression of a dangerous vehicle.^[60] Regardless of any increased risk of fire, the GM trucks had safety records in side-impact crashes statistically indistinguishable from their Ford and Dodge counterparts. The sidesaddle fuel tanks themselves, were found to have a robust design highly resistant to crushing or crumpling from a side impact. Trucks equipped with these tanks met and exceeded the requirements of Federal Motor Vehicle Safety Standard № 301. Studies showed that it would take about 4,000 side-impact crashes with such a truck to get one with fire, major injury, or fatality.^[61]

It was also found that the Dateline report was dishonest about the fuel tanks rupturing and the alleged 30 mph (48 km/h) speed at which the collision was conducted. The actual speed was found to be higher, around 40 mph (64 km/h), and after x-ray examination of the fuel tanks from the C/K pickups used in the staged collision, it was discovered they had not ruptured and were intact.^[62][63]

Fatality figures vary wildly. A study by Failure Analysis Associates (now Exponent, Inc.) found 155 fatalities in these GM trucks between 1972 and 1989 involving both side impact and fire.^[64] The Center for Auto Safety, Ralph Nader's lobbying group, claims "over 1,800 fatalities" between 1973 and 2000 involving both side impact and fire.^[65]

In 1993 the bad publicity generated by the Dateline story spawned several class action lawsuits. In addition GM was sued more than 100 times in lawsuits brought by individuals who were burned in GM trucks.^[66] Nearly all of those cases were settled out of court. In 1993, a Georgia jury awarded more than $105 million, including $101 million in punitive damages, to the parents of a 17 year old named Shannon Moseley who burned to death.^[66] The verdict was later overturned by an appeals court^[67] and the case settled before it could be re-tried.

On Oct. 17, 1994, U.S. Transportation Secretary Federico F. Pena announced that a two-year investigation had found that the trucks posed a fire hazard. Federal officials estimated that 150 persons may have died in preventable fiery crashes. The gas tanks leaked in at least two crash tests performed by GM around the time the trucks were first sold in 1972. The federal report also stated that 50 MPH crash tests performed in the early 1980s "clearly demonstrated" the tanks were susceptible to puncturing. Perhaps influencing the government's decision on whether or not to order a recall is the fact that in the 1980s GM prevailed in court when the federal government ordered a recall over a suspected brake problem. GM and other auto companies were required to meet the National Traffic and Motor Vehicle Safety Act, which requires that they not only meet standards but produce vehicles which operate safely under real conditions.^[68]

GM also settled with the U.S. National Highway Traffic Safety Administration (NHTSA) in 1994 for the amount of $51 million to be used for safety programs. GM also offered owners $1000 coupons toward the purchase of a new truck with a trade-in of the old one.^[67] The fourth-generation C/K-Series pickups of 1988–2001, designed and produced well before the lawsuits, had a new single fuel tank located within the frame rails.{{Clear}}

Foreign production

Sevel Argentina S.A. built the Chevrolet C10 in its Córdoba plant from 1985 to 1991. The gasoline version used the Chevy 250 CID engine (4,093 cc) familiar to most Latin American markets, producing 130 hp. Because of Sevel being a subsidiary of Peugeot, the C10 was also available with a 70 hp Indénor XD2 2,304 cc diesel engine, perhaps best known in the US from the Peugeot 504.

Fourth generation 1988–2000 (GMT400)

Planning for the GMT400 began in the early 1980s. After design freeze, production development began in early 1984 and were introduced in April 1987 as 1988 models (known as the GMT400 platform). For this generation, all trim lines of the GMC full-sized truck were known as the GMC Sierra. There were eight different versions of the C/K line for 1988: Fleetside Single Cab, Fleetside Extended Cab, Fleetside Crew Cab, and Stepside Single Cab models, each in either 2WD (C) or 4WD (K) drive-lines. This extended cab was the first to be offered on a GM pickup. Another significant change was the addition of independent front suspension to all models. Three trim levels were available: Cheyenne, Scottsdale, and Silverado. Engines were a 160 hp (119 kW) 4.3 L V6, a 175 hp (130 kW) 5.0 L V8, a 210 hp (157 kW) 5.7 L V8 and a 6.2 L diesel V8. A 230 hp (172 kW) 7.4 L V8 was available in the 3/4-ton and one-ton trucks. Most of the powertrain was a carryover from the 1987 R/V with fuel injection. To enhance durability the trucks featured extensive use of galvanized steel for corrosion resistance and a fully welded frame with a boxed front section for strength and rigidity.^[71] During the development of the GMT400 platform GM designers based their prototypes on the compact GMT325 S-series (S10 and S15/Sonoma) - upon the official release the GMT400 was the first GM vehicles to use an electronic speedometer and a serpentine accessory drive. Some consider the GMT400 as a scaled-up version of the S10/Sonoma with rounded off contours - later incorporated into the second generation S-series.

In 1989, a Fleetside Sport package was available with matching body color bumpers and grille, chrome wheels, and fog lights. A Z71 off-road package was also available with skid plates and Bilstein shocks. The Work Truck (W/T) was introduced in 1988, which featured a single cab long bed with Cheyenne trim and a new grille with black bumpers. Also in 1988, the GMC 3500 EFI with a fuel-injected version of the 7.4 L V8 became available. The engine produced {{Convert|230|hp|kW|0|abbr=on}} and {{convert|385|lbft|Nm|0|abbr=on}}. In 1991, the 4L80-E automatic transmission was added for 3/4- and one-ton trucks. In 1992, the four-speed manual transmission was dropped and the stepside trucks were available with extended cabs. The 6.5-liter diesel V8 was also made available with a turbocharger. 1994 models received a new front fascia, federally mandated CHMSL, many new exterior colors including a new two-tone option on the rocker panels, and new tire and wheel combinations. In 1993, the 700-R4/4L60 transmission was revised with electronic controls, becoming the 4L60-E. Exterior changes this year included a special two-tone paint option, new gloss black folding exterior mirrors, and the door handles were changed from a smooth gloss black finish to a textured, satin finish.

All 1995 models received a new interior that included a new steering wheel containing a drivers-side airbag, a new dashboard containing a more centrally-mounted radio, dial-operated HVAC system, and an improved gauge cluster. New front door panels and new seats were also included. On the outside, 1995 model C/Ks and Sierras received new exterior mirrors. For 1996, a passenger-side-mounted third door became optional on extended cab models. A new range of engines was included; The "Vortec" series of engines brought increases in power for gasoline V6 and V8 small-block engines. The 6.2 diesel V8 was dropped.

C/K 1500 models received a passenger side airbag for 1997 in order to comply with new federal regulations for light trucks (2500 and 3500 models were exempt). This required a slight dashboard redesign to incorporate these airbags. On models where passenger airbags weren't included, the space was occupied by a storage compartment. Also, 1997 was to be the last year the C/K Silverado would display "CHEVROLET" on the tailgate (although this continued into 1998 on Cheyenne models).

1998 models received a new steering wheel with advanced driver airbag, GM's PassLock anti-theft system, and higher trim models featured a new Chevrolet Silverado badge on the tailgate. Deluxe two-tone paint was discontinued, but conventional two-tone continued as an option.

1999 meant minor trim and badge updates as GM readied the end of the GMT-400 platform. There was some overlap in 1999–2002 model years. In response to continued fleet sales, the GMT400 trucks were produced as the Sierra Classic/Silverado Classic through 1999 and the C/K and Sierra 2500/3500 Crew Cab and chassis cabs were produced through 2000. The big C3500HD chassis cab was the last of the GMT400s and ended production after the 2002 model year. A Brazilian version of the GMT400 was produced in Brazil powered with a Chevrolet inline six, a 4.2-liter I6 MWM Sprint Turbodiesel and a 4.0L I4 NA Maxion Diesel.

The GMT400 and G-Van were the last two platforms to utilize the traditional small-block Chevrolet V8 in the 2002 model year.

The GMT800 platform was introduced in 1999 as the Silverado/Sierra.

1999 models

For 1999, while the Chevrolet Silverado 1500 was all-new, its predecessor, the C/K 1500, was sold alongside the all-new model. Only available in Silverado trim with the two or three-door Extended Cab configuration, the 1999 C/K 1500 included more standard equipment over the 1998 models, such as air conditioning, premium cloth seating surfaces with power lumbar support for both front seats, and the 5.0 L Vortec V8 gasoline engine as standard equipment with the option of the 5.7 L Vortec V8 gasoline engine, both with a four-speed automatic transmission (the manual transmission and gasoline V6 and diesel V8 engine options were discontinued for 1999 for the C/K 1500). Those wanting Regular Cab or less-expensive, lesser-equipped trucks (especially those with a gasoline V6 engine or manual transmission) would now need to opt for the all-new 1999 Chevrolet Silverado 1500.

C/K in Oceania

Holden imported the GMC C/K beginning in 1996, exclusively for ambulance use. Unlike their Holden Suburban siblings, they were not sold to the general public nor did they bear Holden badging ^[72], and they were not built as right-hand-drive at the factory.

Jacab Ambulance in Tamworth purchased the GMCs and converted them to ambulances, and also handled the RHD conversion.

Engines^[73]

Sport Equipment Package (RPO code BYP) ^[74]

In 1989, a Sport Equipment Package was available on either C/K1500 fleetside short-bed single cab models with the YE9 silverado interior trim package. The Sport Equipment Package featured a black grille with a red outlined bow-tie emblem, black moldings outlined in red, body color front and rear bumpers, black mirrors and "SPORT" identification decals on the box and on the tailgate.

The BYP package was only available on trucks painted in solid red, white and black in 1989. It has been reported that the 89 sport was a limited production run set to determine how well the package would be received by consumers in the years to follow. There were no suspension or engine upgrades provided with any of the sport packages as this was an appearance only option. Suspension or any other upgrades or options are only determined by additional RPO codes. It has been rumored that only 5,400 BYP packaged trucks may have been produced in 1989.

In 1990, the Sport was re-introduced and carried on until 1994 along with the 454SS. GMC models could now be optioned with the Sport appearance package with their own unique decals and color combinations. The exterior mirrors became solid, low-profile aerodynamic manual units color matched to the body color. A ZQ8 Sport suspension package was now an available option for 2WD models which included Bilstein Shocks, 12:7:1 ratio steering and required 275/60R15 tires. In 1992 Blazer/Jimmy models could now be optioned with the BYP package. The Sport Equipment Package is the most frequently faked looks for the Chevrolet trucks but RPO decoding will reveal if it is a true "sport" or not.

454SS (RPO code B4U)

In 1990, Chevrolet introduced a high-performance variant of the GMT400 under the Super Sport emblem called the 454SS. It was available only as a 2WD half-ton regular cab short box in Onyx Black only with a garnet red interior. The 454SS was powered by a {{convert|454|cuin|L|1|abbr=on}} V8 producing {{Convert|230|hp|kW|0|abbr=on}} and {{convert|385|lbft|Nm|0|abbr=on}}.^[75] A 3-speed automatic transmission (Turbo Hydra-Matic 400) and 3.73 rear axle ratio added to the truck's performance. The axle itself is unique, being a 14-bolt semi-floating unit which uses standard Chevrolet 5 on 5-inch wheels—the only factory-produced 14-bolt axle with such a wheel bolt pattern. The suspension was also upgraded with {{convert|32|mm|in||abbr=on}} Bilstein gas-filled shock absorbers, a {{convert|32|mm|in||abbr=on}} front stabilizer bar, and 12.7:1 fast-ratio steering gear assembly.

Unique exterior features included a front air dam with fog lights, special rims, decals displaying "454SS" on the bed sides, red trim emblems, and black painted grille, bumpers, and mirrors. The interior was also unique with a special plush Garnet Red cloth with black trim, high-back reclining sport bucket seats, and center console.

For 1991, a four-speed electronic automatic transmission (known as the 4L80E), 25 more horsepower, and even higher torque (405 lbs/ft at 2400 rpm) were added to the 454SS. The rear-axle ratio was also lowered to 4.10:1 for extra jolt off the line. On the dash was a tachometer, oddly omitted from 1990 models. Dual exhaust was also added during the '91-'93 model years.

The MSRP of the 1990 model was US$18,295 with a $550 destination charge. A total of 16,953 units were sold over the 4 years the 454SS was in production, with 1990, the first year of production, selling 13,748 units alone. The 454SS was discontinued after the 1993 model year.

In 1992–1993 other color options included Summit White and Victory Red, with multiple interior colour options. The rear quarter panel and tailgate decals also changed in 1992 to a more 'stylized' 'SS' and the Chevrolet sticker on the tailgate became much smaller and located on the corner area.

C3500 HD

In 1991, GM introduced a 15,000 pound GVWR C3500 HD model under both the Chevrolet and GMC nameplates. It was positioned to bridge the gap between light-duty and medium-duty trucks. It was only offered as a standard chassis cab until 1996 when a crew chassis cab was also offered. It is not clear if the crew cab was for fleet orders only, or if it was available to the general public. An extended cab was never offered, though such conversions have been done. All paint colors and most options were offered in the C3500 HD. Upper cab marker/clearance lights were not optional equipment on the C3500HD. The two mirror options are the camper style and west coast style mirrors.

The common drive axle used on the C3500 HD was the Dana 80, an 85.8-inch-wide full floating axle with an 11-inch ring gear fitted with 19.5–inch x 6.0 wheels. The front axle was a solid I-beam drop axle, similar to the axles of medium and heavy duty trucks. Both front and rear leaf sprung axles had disc brakes.

Available wheelbases were 135.5, 159.5, and 183.5 inches (3442, 4051, and 4661 mm). The C3500 HD used a different frame than the C/K3500 cab and chassis. The C/K3500 cab and chassis and C3500 HD rear frame rails are spaced at industry standard 34 inches for easy fitment of bodies but that is where the similarity ends. The HD frame is much heavier and exits straight out behind the high mounted cab necessitating the unmistakable HD filler panel between the bumper and grille. The front fenders were also equipped with the same flares used on 4x4 models of the lighter trucks to cover the increased track width and larger tires.

Two transmissions were offered in the C3500 HD; the 4L80E 4-speed OD automatic, and the NV4500 5-speed manual.

There were also Brazilian versions of the C3500 HD, offered in the domestic market only as a GMC and in regional export markets (basically Argentina and Uruguay) as Chevrolet. These versions were badged in a different way than its American counterparts, as 6-100 and 6-150 according to their approximated GVWR in metric tonnes (a little above 6 tonnes) and the power in PS (100PS for the 4-cylinder version fitted with a Maxion S4 engine and 150PS fitted with the MWM Sprint 6.07TC), always bolted to a 5-speed manual. A version of the short-bed C2500 used the GMC 3500 HD nameplate only between 2000 and 2001 and fitted with the MWM engine, as it had the GVWR increased to 3500 kilograms in order to be classified as a truck in Brazil to attract lower taxes and annual licensing fees.

GM never offered a four-wheel-drive K3500 HD counterpart of the C3500 HD. Several aftermarket conversion companies offered a 4x4 version with either a Dana 60 or Dana 70 front axle. At least one company, Monroe Truck, was offered by GM dealers as a ship-through 4WD upfit using the RPO code VCB. Tulsa is another company that did 4x4 conversions for utility companies. Quigley conversions were mostly for fire/ambulance applications.

Engines 1991–2000

Engine offerings for the C3500 HD included three gasoline engines; from 1991 to 1995 5.7L 350 Small Block and 7.4L GEN V Big Block. In 1996 both the 5.7 and GEN V 7.4 were replaced by the new Gen VI 7.4L Vortec Big Block.

One of the main additions to the 1991–2000 years is that it introduced the 305 cu in a traditional 5.0L V8 and also in a 5.7L V8 which was most common in the SLE packages.

The RPO L65 6.5L Turbo Diesel debuted in the C3500 HD in 1991, the year of the engine's release. The 6.5 was the only diesel engine offered for the entire production run of the T400 C3500 HD. No diesel was available for 1991, the first C3500 HD production year.

Engines 2001–2002

While all other C/K pickup models were dropped by 2000, the C3500 HD was produced until 2002 due to fleet demand. In the brochures it is referred to as Sierra Classic/Silverado Classic. There were two engine choices: the 8.1 L Vortec V8 replaced the Gen VI 7.4 L Vortec, while the venerable 6.5 L Turbo Diesel continued.

Wheels

GMT400 Trucks were sold with 15 inch wheels on C1500 models, 16 wheels on all other models, except the C3500 HD which had 19.5 inch wheels.

Bolt patterns for the wheels are:

C1500 - 5 x 5"

K1500, CK2500 Light Duty - 6 x 5.5"

CK2500 HD, CK3500 - 8 x 6.5"

C3500 HD - 10 x 7.25"

Hollander 1366 - steel 19.5 x 6 inch, 10 lug, dually wheel, C3500 HD only

Hollander 1618 - cast aluminum 16 x 7 inch wheel, 6 lug K1500 "4x4" wheel

Hollander 1619 - steel 16 x 6.5 8 lug CK2500HD, CK3500 Non-dually wheel

Hollander 1621 - steel 16 x 6.5 inch 6 lug wheel, 2400 pound rating at 80 psi

Hollander 1622A - steel 16 x 6.5 inch 6 lug wheel, 1550 pound rating at 55 psi

Hollander 1622B - steel 16 x 6.5 inch 6 lug wheel, 2400 pound rating at 80 psi

Hollander 1670A - chrome steel 15 x 7 inch 5 lug wheel offered on 454SS C1500 model

Hollander 1670B - painted steel 15 x 7 inch 5 lug wheel, spare for 454SS

Hollander 1740 - Cast aluminum 15 x 7 inch 5 lug wheel offered on 1988-1992 C1500 models in very limited numbers

Alcoa XXXX 16 x 7 inch 6 lug forged aluminum wheel - used on 2000 Tahoe Z71

Ronal R36 - 16 x 7 inch cast aluminum 5 spoke, 5 lug wheel, 2000 Tahoe Limited

Brazilian versions

A variant of the C/K family was introduced in Brazil during the 1960s. These used the instrument cluster from the 1960–66 US Chevrolet C/K series although the exterior sheet metal layout is exclusive to Brazil. The models built included a light truck, named C-10, and an SUV named Veraneio (initially known simply as Chevrolet C-1416),^[76] introduced in 1964. They were initially powered with a Chevrolet {{convert|4.2|l|cuin|abbr=on}} inline six based on the pre-1962 "Stovebolt" engines. Later they used the {{convert|250|cuin|l|abbr=on|order=flip}} engine from the Chevrolet Opala. In later years a four-cylinder diesel (Perkins Q20B) was also offered labeled as D-10 (light truck only). An ethanol-powered version of the C-10 was offered beginning in the 1981, dubbed the A-10.

After 1985, a redesigned pickup with the same cabin structure of the U.S. 1973–87 C/K truck but with a different front clip bearing more resemblance to the Opel-based Brazilian Chevrolets of that time was introduced as the C-20, powered with the {{convert|250|cuin|l|abbr=on|order=flip}} inline six of the U.S. Chevy II/Nova. Diesel and ethanol versions were also sold, labeled as D-20 and A-20 respectively (later models of the D-20 replaced the Perkins Q20B with a Maxion S4). The original version of the Veraneio was kept in production until 1988 (model year 1989), but it was eventually replaced with an updated version based on the C-20 family.

In 1997 GM introduced officially in Brazil and Argentina the then-current Silverado pickup, but only in C2500 with a regular-cab short-bed bodystyle, which lasted until 2001, and in late-1998 came the Tahoe, which in Argentina and Brazil was badged Grand Blazer. In late-1999 the production of the Silverado was switched from Argentina to Brazil, and the Grand Blazer was simply phased out. The {{convert|4.1|L|cuin|abbr=on}} inline six engine with {{convert|138|hp|kW|0|abbr=on}} was offered on both models with option for a MWM {{convert|4.2|L|cuin|abbr=on}} turbo diesel engine producing {{convert|168|hp|kW|0|abbr=on}}. But the model earned a reputation for being a less capable work vehicle than its predecessor. After the Silverado was discontinued in Brazil, GM ceased offering any full-size truck in Brazil.

See also

• Chevrolet Silverado / GMC Sierra

References

External links

• The scandal of punitive damages. Titled: "The Most Dangerous Vehicle On the Road", Wall Street Journal, February 9, 1993, By Walter Olson

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