When faced with transmission maintenance, repair or replacement, it is vital to know which transmission came in the car. When it comes to similar General Motors products of the late 1970s, there is a high degree of interchangeability among parts, so there are many times when a GM ransmission isn't the one that came in the car, but still does the job just the same.
The Vehicle Information Kit for the 1978 Chevrolet Camaro at the GM Heritage Center website shows that the 305-equipped Camaro LT was offered with either the MM4 Muncie four-speed manual transmission, or the MX1 Turbo Hydramatic 350 three-speed automatic transmission.
For the purposes of exchanging transmissions for rebuild or transplanting one from another car, it is important to remember that GM used different lengths of transmission tail shafts to enable the use of the same model of transmission on different vehicles. Check with an automatic transmission shop to find out which length of tailshaft housing was used on your car.
Another important thing to keep in mind with the Camaro and the Firebird of this period is that there is a weighted torque arm that mounts to the rear of the transmission. If you are installing a transmission to replace a missing one, you will need a transmission with the proper mounts on the tailshaft for the torque arm.
