Originally Posted by ncopp
Will the t-5 transmission work in a 79 cj5 with 258. It has a three speed now. If so what all has to be changed?
Ugh. Even though Jeep installed these in CJ5's in the 80's it was always a marginal trans, IMO.
If you're going to all the trouble to swap an O/D trans into your CJ, why don't you consider a NV3550? It's a medium duty 5sp with O/D, that is way better than any T5 ever installed in a CJ. (Note: The WC T5 wasn't installed in the CJ's, IIRC, and the ratios are different.) The NV3550 was used by Jeep starting in the 2000 TJ's.
Adapt it to your Dana20, or swap in a Dana300 (or Atlas/STaK). As noted there will be driveshaft/crossmember modifications. And some floor pan trimming.
If you don't want the O/D, I'd seriously consider locating a T176/Dana300 combo and swap the whole thing into the CJ. The T18/NP435 swap would be my recommend if you want the 'granny' 1st gearing. If you want something 'in between' the T18/NP435 and the T176, look into a T19.