The C4 3-speed automatic is the most popular transmission for the V8 swap. Three different length C4 adapters eliminate the need for driveshaft modifications. To determine which adapter you need, measure the overall length of your existing trans assembly from the back of the engine block to the front of your transfer case, then match the closest possible length below. The transmission code numbers can be checked, but keep in mind the tag on the door may not match the vehicle. Therefore, checking the physical length is preferred. When using a C4 with a 5.0L, its best to use an engine control computer that came with a manual transmission, as they don't require input from transmission sensors.