1981 Chevrolet Ck Custom Step-side Pickup Truck on 2040-cars

Third Generation Chevrolet 1973–1987

Third generation

Also called	Chevrolet Scottsdale Chevrolet Custom Deluxe Chevrolet Silverado (South Korea)
Production	1973–1987
Assembly	Atlanta, Georgia Baltimore, Maryland Pontiac, Michigan Flint, Michigan Tarrytown, New York Kansas City, Missouri St. Louis, Missouri Janesville, Wisconsin Norwood, Ohio Fremont, California Oshawa, Ontario C'ordoba (Argentina) Arica, Chile (1975–1982) Ulsan, South Korea
Engine	250 cu in (4.1 L) I6 292 cu in (4.8 L) I6 262 cu in (4.3 L) V6 305 cu in (5.0 L) V8 350 cu in (5.7 L) V8 400 cu in (6.6 L) V8 454 cu in (7.4 L) V8 350 cu in (5.7 L) Oldsmobile Diesel V8 379 cu in (6.2 L) Detroit Diesel V8
Transmission	3-speed Turbo Hydra-Matic 350automatic 3-speed Turbo Hydra-Matic 400automatic 4-speed Turbo Hydra-Matic 700R4automatic 3-speed Saginaw manual 4-speed Saginaw Muncie SM465 manual 4-speed New Process NV833 overdrive manual
Wheelbase	117.5 in (2,985 mm) 135.5 in (3,442 mm) 164.5 in (4,178 mm)
Length	188.5"(1971), 191.5"(1975), 211.8"[3]

Facelifted GMC C/K

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.^[10] 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 theglass.^[6][11][12]An all-new clean sheet redesign of General Motors' Chevrolet and GMC brand C/K-Series pickups d'ebuted 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.^[4] 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.^[5] As a result, the third generation trucks are officially known as the "Rounded-Line" generation.^[6][7][8][9] Some people may refer to them as "square bodies", given that the trucks appear square-like when compared to more modern automotive design standards.

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.^[13]

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 one-ton pickups, along with a new Crew Cab option on the 164.5 in (4,178 mm) wheelbase.^[14] 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 player could be purchased, along with a CB radio.^[15]

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.

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.^[17] From model years 1973 to 1977, chestnutwood 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.^[18] A Delco AM/FM audio sound system and an all-season climate control system that heated, cooled, cleaned, and dehumidified were optional extras.^[19]

At its launch in 1972, the Rounded-Line 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.^[4][20][21]

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.^[22] 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.^[23][24]

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.