I would like to know what it would take to swap a 4spd auto in place of a 3spd. The parts I've heard are the trans, tr. case, drive shafts, and both diff's (front and rear). I don't understand why the differentials would need to be changed. I can't find the 3spd anywhere. and the OD would be nice incase I need to drive it to work (50 miles round trip).

The current trans is not shifting past first. I know nothing on automatics besides pulling and installing. A flush helped none, so I figure it's toast. It's also a b#&%* to get into 4 wheel high, and won't go into low at all, so that needs work too. The the starter is loose and won't stay tight. Oh boy do I have some learning to do. I look forward to it, and thank you in advance for the teaching.

 

Will 2wd trainies work? What would I need to get to make it all go together? (sorry fort the double post, should've editted)