GM Full-Size Trucks 1970-1979 Repair Guide



Most 3-speed transmissions used are the very similar Saginaw and Muncie side cover units. These may be told apart by the shape of the side cover. The Saginaw has a single bolt centered at the top edge of the side cover, while the Muncie has two bolts along the top edge. Some 1976-80 models use the top cover Tremec 3-speed. All 3-speed transmissions use side mounted external linkage, with provision for linkage adjustment, and a column shift.

The Muncie CH465 with synchronized 2nd, 3rd and 4th gears is the standard 4-speed transmission for 1970 and later. The transmission is distinguished by its top cover and the absence of external linkage. In addition, the New Process 435CR close ratio 4-speed transmission was available on all 1 / 2 and 3 / 4 ton models in 1970. It was also available in 1971 in those trucks, but only with the 350 engine. The 435CR is also a top cover unit, with no provision for linkage adjustment.