which bearings? axle or carrier? axle bearings are no big deal, carrier bearings are a bit more complicated. the track lock clutches are good for about 100k, or so I have been told.
I would put whatever you found in the jeep and run it for a while, at least untill you can see a new differential and axles in your future. The worst that can happen is you crater the carrier and you end up needing a new locking differential. You can build up an
AMC20 for pretty close to what the
Dana 44 would cost and for $
AMC 150 you got the housing and brakes you need to start with. You need to tack weld the tubes and truss the axle and then do a locker with one piece axles. Start with the axle in the Jeep then do the one piece and by that time you may have worked up the knowlage and confidence to put a new diferential in it. The parts are expencive but the labor is outragious. The big thing to remember, IMHO, is that the guys that set up rear axles earn every cent.