Originally Posted by H-townbenzoboy

The 1981 300TD used the 722.303 transmission, which is the same transmission that the W126 chassis 300SD used for most of its production run. You can put a 722.315 transmission in there from a 82-84 300D Turbo, 300CD or 300TD Turbo, but you'll have to swap out the tailcones to accomodate the 1981 300TD's electronic speedometer. If you want to save yourself the labor involved in a tailcone swap, look for a 722.303 from either another 1981 300TD Turbo or a 81-84 300SD.