Hello Robert. Well, let me say "probably". I got The O.D. a while ago and it was not attached to a gearbox. At the same time, I got a couple of free wheeling units and a T83 and half of a T81 . Half because the actual trans case was somehow ripped away from the bell housing, leaving the mounting flange on the bell housing, which was then lost to time who knows when. Anyway, the O.D. and gearbox I have were likely never together. But who knows? On a separate but related topic, I'd like to ask the guys and gals out there what they would use on their car? Free wheeling or Overdrive? My car is a Commander, so I was going to use the F.W. as that's how it was built. Any thoughts out there? Thanks!