Year-To-Year Differences
- 1973 Chevy C10/GMC K10 Differences
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.
- 1975 Chevy C10/GMC K10 Differences
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.
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. These replaced the outdated and inadequate lap belts previously used.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.
- 1976 Chevy C10/GMC K10 Differences
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.
- 1977 Chevy C10/GMC K10 Differences
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.
- 1978 Chevy C10/GMC K10 Differences
The addition of the first diesel engine of the three American automakers in a light-duty pickup the 125 hp 350 cu in (5.7 L) Oldsmobile diesel V-8 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 wood grain inserts were replaced by bright brushed aluminum.
- 1979 Chevy C10/GMC K10 Differences
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).
The wood grain inserts were replaced by bright brushed aluminum.
- 1980 Chevy C10/GMC K10 Differences
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.
The wood grain inserts were replaced by bright brushed aluminum.
- 1981 Chevy C10/GMC K10 Differences
A mid-life cycle cosmetic facelift and mechanical refresh were 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 re-sculpt the front end with new sheet metal, reducing areas that could hinder airflow 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-tier halogen headlamps became available with the Deluxe Front Appearance package. 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 dropped from the half-ton class pickups, except in California where it was offered in place of the new 5.0 L 305 engine with electronic spark control, which did not meet California’s emissions requirements.
A new Shift-on-the-move four-wheel-drive system with a two-speed dual range New Process 208 aluminum 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. 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 directly synchronized gearing. Four Low applied reduction gearing. The front and rear propeller shafts were locked at all times in Four High and Four Low. Neutral was provided for the 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 379 cu in (6.2 L) Detroit Diesel V-8 was added to replace the LF9 Oldsmobile diesel. Chrome front bumpers were now standard on base models.
- 1982 Chevy C10/GMC K10 Differences
A new four-speed Turbo Hydra-Matic 700R4 transmission with overdrive gearing became available.
- 1985 Chevy C10/GMC K10 Differences
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.
- 1987 Chevy C10/GMC K10 Differences and 1987-1991 R/V Series
For the 1987 model year, the last model year for the conventional cab pickups, the Rounded-Line C/K-Series was renamed the R/V-Series. R-Series now designated two-wheel drive, while V-Series represented four-wheel drive. The name change is also found in the vehicle identification number. 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 on 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.
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” power train 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. The 5.7 L 350 cubic inch pushrod V-8 was reintroduced 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 were increased to 210 hp, and 300 lb-ft of torque.
After 1987, R/V remained in use for the Rounded-Line one-ton crew cab pickups through 1991 (built at Janesville), 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.
