History

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. 1970 GMC C/K. 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 1970's 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. 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. 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. 1972 GMC Sierra Custom Camper. 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.

Engines Trim Levels (Chevrolet) A 10, 20, or 30 on the emblem indicates 1/2, 3/4, or 1 ton trucks.

Trim Levels (GMC) 1500, 2500, and 3500 designations were used to indicate 1/2, 3/4, and 1-ton trucks.

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