rebuild or replace ?

I have a 1986 vette with the 4/3 transmission. It seems to be stuck in reverse and the overdrive had stopped working. I don't know whether I should rebuild or do a transmission swap. Any experience and suggestions would be helpful. 

                                                                                                        Thanks, Dustidu aka (parked)

Hi, Just my two cents. I think I would replace it with a six speed. The 4+3's are not as good. But if you are O.E.M. type, by all means rebuild it. 

 I am wondering if someone in the group has actually done a 4/3 to T-56 or T-5 trans swap. Looking for some first hand information and experience. Thanks to everyone.  dustidu   💯

I have no experience with the 4+3, never even been in a car that had one.  The ZF 6 speed that replaced it is pretty robust.  Whether or not one would bolt up to your engine is a question that Mr Apple may have an answer for.

If originality is a priority for you then rebuild it, but if you're looking for drivability then replace it, imho.

I would first find out why it appears to be "stuck in reverse". Do you mean the shifter itself will not come out of reverse, or does the shifter move, but the trans stays in reverse? Two different problems, with different solutions. 

As far as the O/D not working, that could  something as simple as a fuse/relay, or other electrical issues. Could also be the O/D section has failed mechanically. The 4 speed part of the trans is an easy rebuild if needed. The O/D section, however, is something totally different. Parts are still available for the O/D section(I have a box with a complete O/D section here somewhere), but finding someone capable, and knowledgeable enough to build it without causing even more damage is hard to do. I've built my fair share of them over the years....and hated every one...but the satisfaction of seeing them work properly is well worth the headache. Money-wise, repairing the 4+3 would be the cheaper route. Swapping in a T56 is quite a chore....and expensive. If you can get the complete swap kit from a reputable vendor, that would be the way to go. Even then, problems always seem to appear. I know of a couple of guys that have done the T56 swap in the C3 era cars that love it....once they got all of the parts needed, and got it all sorted out.

So...my opinion would be to find out what is actually wrong with the reverse issue first....might well be a very simple fix. Then, go after the O/D operation, and see what might be the issue with it. A little diagnostic time could save tons of cash.