To mount the tranny to the motor, the bellhousings are different. In the case of our Valiant, we didn't want a three-speed tranny for obvious reasons. So we bought a 23-spline 833 tranny from a friend for $200. Since we needed a bellhousing, another friend sold us a Lakewood safety bell for $40. It may be heavier than the factory unit, but keeping the flywheel from coming up through the floor like a buzz saw seemed kind of important. It pays to ask what your buddies have sitting in their garages while doing this type of stuff.