Found this info tonite while I was surfing...thought I would pass it on.
1967-1972
A much more modern truck graced showrooms for 1967 as a complete restyle took place. A clean, broad-shouldered look was the main theme, and both Fleetside and Stepside body styles were again offered. A new Custom Sport model debuted, featuring bucket seats with a center console. Long-bed models no longer had a separate name; they were simply called long beds.
1968 brought side marker lights, a 307 V8 (which replaced the 283), a bit more chrome trim and a 50th anniversary edition that featured gold and white two-tone paint.
A new grill with a wider horizontal centerpiece and a foot-operated parking brake (which replaced the former hand brake) updated the pickup line for 1969. A trio of new V8s became available this year; a pair of 350s with either 300 or 350 horsepower and a 396 with 310 ponies but more torque than the smaller V8s. GMC introduced a Super Custom model with slightly upgraded interior and exterior trim.
Changes for 1970 included a few new options such as a tilt steering wheel and a stereo with eight-track player. And, for the first time, the shiftless masses could operate the four-wheel-drive models thanks to the newly available three-speed automatic transmission.
A new egg-crate grill graced the front of the 1971 pickups. New trim level names debuted, including the base Custom, the mid-level Custom Deluxe (formerly the Custom) and the Cheyenne (formerly the Custom Sport Truck).
Interior refinements, such as molded door panels and an optional Highlander seat trim, took place for 1972.