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Chevrolet C/K

The C/K is the name for Chevrolet and GMC's full-size pickup truck line from 1960 until 1999 in the United States, from 1965 to 1999 Canada, from 1964 through 2001 in Brazil, and from 1975 to 1982 in Chile. The first Chevrolet pickup truck appeared 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 in 1999 in the US and Canada, and 2001 in Brazil; the Chevrolet Silverado HD and GMC Sierra HD heavy-duty pickup trucks followed in 2001.

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

First generation 1960–1966

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 was the 3100, 3200, and 3600 designations for short 1/2, long 1/2 and 3/4-ton models. Instead, a new scheme would assign a 10, 20, or 30 for 1/2, 3/4, and 1-ton models. Since 1957, trucks were available from the factory as 4-wheel drive, and the new class scheme would make this known. A C (Conventional) in front of the series number would indicate 2-wheel rear drive while a K would denote 4-wheel drive. Actual badging on trucks still carried the series name system from the previous generation. The 10, 20, and 30 series (C or K) were badged as "Apache 10", etc. 40, 50, and 60 series trucks were badged as "Viking 40", and the largest 70, 80, and 90 series models were marked "Spartan 70" etc. in 1960, C/K trucks were available in smooth "Fleetside" or fendered "Stepside" versions. GMC called these "Wideside" and "Fenderside." Half-ton models were the C10 and K10 short-bed trucks, and C15 and K15 long-bed trucks. 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 had the "K" designation. The 1962 model used torsion bar front suspension, with trailing arm suspension rear. 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 changed for 1964, with elimination of the "wraparound" windshield and a new front grille design, along with various interior changes. Air conditioning and a 220 hp (164 kW) 327 in³ (5.4 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.

Second generation 1967–1972

A new, more modern look came in 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 and 20 series Chevrolet trucks from 1967 to 1972 were built 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 models came standard with leaf springs with coils springs optional; all four-wheel drive models (Chevrolet and GMC) had leaf springs on both axles. This was the only year of the "small rear window"; it was replaced with larger rear glass in 1968. The standard drivetrain came with a three speed manual transmission and one of two engines; the 250 in³ straight six or the 283 cu in (4.6 L) V8. The optional transmissions were the four speed manual, the Powerglide and the Turbo-Hydramatic 350 and 400. The 292 six and the 327 in³ V8 were the optional engines. The 1/2 ton trucks came with a 6 x 5.5" bolt pattern, the 3/4 and 1 ton trucks came with an 8 x 6.5" bolt pattern.

In 1968, the 283 cu in (4.6 L) V8 was replaced with a 307 cu in (5.0 L) and a 310 hp (231 kW), 396 cu in (6.5 L) V8 was offered for the first time. The most visible change in differentiating a 1968 from a 1967 was the addition of side-marker reflectors on all fenders. Also, the small rear window cab was no longer available. 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 truck manufacturing, and to commemorate, they released a 50th Anniversary package, which featured an exclusive white-gold-white paint scheme. Also in 1968, the Longhorn model debuted on 3/4 ton trucks. Featuring a 133" wheelbase identical to the one ton vehicles, it added an extra 6" to the bed. Longhorns, interestingly, were 2wd only; no factory Longhorn 4x4 was built.

The 327 c.i. V-8 engine was enlarged in 1969 to 350 CID (stroke increased from 3.25 to 3.48) with a net horsepower rating of 195-200, depending on emissions package 255 hp (190 kW), 350 cu in (5.7 L). 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 104 inches (2,642 mm). 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 only noticeable change for 1970 was a minor update to the Chevrolet grille. At first glance, the 1969 and 1970 grilles appear identical. However, the 1970s plastic inserts actually have highlights that break the appearance into six separate sections. The 396, while still sold as such, was enlarged to 402 cubic inches starting in 1970.

Several 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 referred to as 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. Nineteen seventy-one 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. While many 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" 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). Also, Chevrolet changed the 396 V8 emblem designation to 400 V8.

The 1972 models were virtually identical to 1971 models, with the only change being the rear view mirror was glued to the windshield instead of being 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.

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 débuted in 1972 for the 1973 model year. Development of the new third generation trucks began in 1968, four years prior to production in 1972, with vehicle components undergoing simulated testing on computers, before the first prototype pickups were even built for real world testing. The redesign was revolutionary in appearance at the time, particularly the cab, departing from typical American pickup truck designs of the era. As a result, the third generation quickly became known as the "rounded-line" generation; although some people refer to them as "square bodys", given that the trucks appear square-like by more modern standards.

GM's design engineers fashioned the "rounded-line" exterior in an effort to improve aerodynamics and fuel efficiency, using wind tunnel technology to help them sculpt the body. Third generation design traits include "double-wall" construction, sleek sculpted body work, flared secondary beltline and an aerodynamic cab which featured rounded doors cutting high into the roof and steeply raked windshield featuring an available hidden radio antenna embedded into the glass.

There were two types of pickup boxes to choose from. The first type, called "Fleetside" by Chevrolet and "Wideside" by GMC, was a "double-wall" constructed full width pickup box and featured a flared secondary beltline to complement the cab in addition to new wraparound tail lamps. 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.

The wheelbase length was extended to 117.5 in (2985 mm) for the short wheelbase pickups, and 131.5 in (3340 mm) for the long wheelbase pickups. A new dual rear wheel option called "Big Dooley" was introduced on 1-ton pickups, along with a new Crew Cab option on the 164.5 in (4,178 mm) wheelbase. Crew Cabs were available 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 could be purchased, along with a CB radio.

The rounded-line generation ultimately ran for a lengthy 15 model years (1973–1987) with the exception of the Crew-Cab, Blazer, Jimmy, and Suburban versions, which continued up until the 1991 model year.

Chassis and powertrain

Third generation rounded-line C/K-Series pickups gained an all-new, high tensile strength carbon steel ladder type frame with "drop center" design. Available driver control systems included hydraulic variable ratio assisted steering and hydraulic Hydro-Boost 4-wheel power assisted brakes, which consisted of front self-adjusting disc brakes and rear finned drum brakes. Engines choices initially consisted of six or eight cylinder engines with either manual or Turbo Hydra-Matic transmissions.

C-Series pickups included standard two-wheel drive with an independent front suspension (IFS) featuring contoured lower control arms to improve durability and ride comfort. The standard rear live axle came with leaf springs in addition to staggered shock absorber placement to help reduce the wheel hop during hard acceleration.

K-Series pickups included either part-time four-wheel drive or permanent full-time four-wheel drive. Regardless of part-time or full-time, all K-Series pickups came with a front live axle, replacing the IFS setup on the C-Series pickups. K-Series pickups featured an off road-oriented design, with the transfer case bolted directly to the transmission and running gear pushed up as high as possible under the vehicle to achieve a low silhouette and optimal ground clearance. Exposed brake lines were wrapped in hardened steel and underbody skid plates were available for further protection.

Part-time four-wheel drive pickups featured manual locking hubs and a two-speed (dual range) New Process 205 transfer case with permanent 50/50 torque split via automatically locking the front and rear drive shafts together.

Permanent full-time four-wheel drive pickups featured a two-speed (dual range) New Process 203 transfer case with locking center differential. The center differential allowed for full-time operation and could be locked to achieve a permanent 50/50 torque split via locking the front and rear drive shafts together.

A locking rear differential from Eaton became available on all two and four-wheel drive pickups as an option, under the "G80" regular production option (RPO) code. It was designed for slow speed off road or low traction conditions. The rear differential featured mechanical slip sensing in addition to a governor, and would automatically lock at or below 15 mph. Unlike a more on road friendly limited-slip rear differential that can operate at any speed, the governor would unlock the rear differential as well as prevent it from locking at speeds above 15 mph for safety reasons, such as the vehicle being on dry pavement.

For 1975, the 185 hp 400 cu in (6.6 L) small-block V8 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, 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.

The addition of the 125 hp 350 cu in (5.7 L) Oldsmobile diesel V8 began in 1978. 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.

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).

Some 1980 models had 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, and cloth-upholstered deluxe models had a new seat fabric.

Trim levels for Chevrolet and GMC were:

  • Custom ('73-74)-Custom Deluxe ('75-87)/Sierra — base model. Rubber floor mat, white painted bumpers and (through 1977) hubcaps, body-colored mirrors, patterned vinyl seats, no headliner, manual door locks/windows.
  • Custom Deluxe ('73-74)-Scottsdale ('75-87)/Sierra Grande — chrome trim, cloth or pleated vinyl seats (a choice was offered) everything the previous trim level has
  • Cheyenne/High Sierra — woodgrain ('73-77) or brushed aluminum ('78 up) interior accents, cloth seats, chrome trim, carpet, headliner, more sound deadening/insulation (inside door panels, in the headliner, etc.).
  • Cheyenne Super ('73-74)-Silverado ('75-87)/Sierra Classic — Extra woodgrain interior accents ('73-77), everything the previous trim level has, more chrome (i.e. bumpers and mirrors), tilt wheel, power doors/windows, and optionally cruise control.

1981 mid-lifecycle facelift

A mid-lifecycle 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. 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 halogen sealed-beam headlamps became available as an option. Mechanical updates included more anti-corrosion techniques, reduced weight, and a new 5.0 liter 305 cubic inch V8 with electronic spark control.

An all-new part-time "shift on the move" four-wheel drive system was introduced on K-Series pickups as a replacement for the permanent full-time four-wheel drive on pre 1981 models. It featured new automatic self-locking hubs and a 2-speed (dual range) New Process 208 aluminium transfer case with permanent 50/50 torque split via automatically locking the front and rear drive shafts together. The transmission and transfer case were synchronized, such that the truck could be shifted from two-wheel drive to fully locked four-wheel drive at speeds of up to 25 mph.

Traditional part-time four-wheel drive was still available with manual locking hubs. 1-ton K-Series pickups still received the 2-speed (dual range) New Process 205 transfer case.

A new 4-speed Turbo Hydra-Matic 700R4 transmission with overdrive gearing became available in 1981 for the 1982 model year. The 151 hp 379 cu in (6.2 L) Detroit Diesel V8 was added to replace the LF9 Oldsmobile diesel. The Cheyenne package was dropped. Chrome front bumpers were now standard on base models.

1985 saw the new 262 cu in (4.3 L) LB1 introduced to replace both inline-six engines. Hydraulic clutches were introduced. Also, a new grill was used. The most expensive radio was the AM/FM stereo seek/scan with cassette tape at $594.

A variation of the C/K series was introduced in 1985 in Brazil, replacing the locally-produced C10, introduced in 1964.

TBI fuel injection was added for 1987. Also for 1987, GM changed the C/K nomenclature to R/V (this is found in the 5th VIN digit). 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. After 1987, R/V remained in use for the full ton 30/35 models, V30/35 regular cab dually, and crew cabs through 1991 (built at Janesville), and SUVs (Chevrolet K5 Blazer and Suburban, built at Flint) through 1991. From 1988 on C/K was used for the fourth generation "GMT400" design.

Sidesaddle fuel tank controversy

The third generation of GM's full-size pickup line featured a design improvement that saw some criticism long after the model run ended. The fuel tank was relocated from the cab to outboard sides of one or both frame rails beneath the cab floor extending under the leading edge of the bed, commonly referred to as sidesaddle. This enlarged fuel capacity from 16 up to 40 gallons depending on wheelbase and the number of tanks. This also removed the tank from the passenger compartment.

According to a now debunked 1993 report which aired on Dateline, this placement made the trucks capable of exploding when involved in a side impact accident. 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 fitting gas cap to create the impression of a dangerous vehicle. GM soon sued NBC over the false report, with the broadcaster settling the same day.

Fatality figures vary wildly. A study by Failure Analysis Associates found 155 fatalities in these GM trucks between 1973 and 1989 involving both side impact and fire. The Center for Auto Safety, Ralph Nader's lobbying group, claims "over 1,800 fatalities" between 1973 & 2000 involving both side impact and fire. Other commentators noted that regardless of any increased risk of fire, the GM trucks had statistically indistinguishable safety records in side-impact crashes from their Ford and Dodge equivalents.

In 1993 the bad publicity generated by the later debunked Dateline story spawned several class action lawsuits. As settlement GM offered owners $1000 coupons toward the purchase of a new truck with a trade-in of the old one. Even though the trucks met NHTSA 15 and 20 mph side impact crash test standards in place at the time of manufacture GM eventually settled with the NHTSA in 1994 for the amount of $51 million to be used for safety programs. The Fourth Generation (1988–2001) was designed and produced well before the lawsuits with one fuel tank inside the frame rails.

Foreign production

Sevel Argentina S.A. built the Chevrolet C10 in their 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.

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 a SUV named Veraneio (initially known simply as Chevrolet C-14/16), introduced in 1964. They were initially powered with a Chevrolet 4.2 l (260 cu in) inline six based on the pre-1962 "Stovebolt" engines. Later they used the 4.1 l (250 cu in) 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 alcohol-powered version of the C-10 was offered beginning in the 1981, dubbed the A-10.

After 1985, a redesigned pickup similar to the U.S. 1973-87 C/K truck was introduced as the C-20, powered with the 4.1 l (250 cu in) inline six of the U.S. Chevy II/Nova. Diesel and alcohol 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.

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