Here is the scenario:

I have 2 4cyl 8" thirds, one with 4.88s and a LSD, and junk 5.71s and a locker. I want the locker in the 4.88 third. can i simply swap the carriers and ring gears? or is that a bad idea and should I instead disassemble the carrier and swap the guts and pins and springs etc?

Hopefully someone has done this and can prevent me from potentially doing something bad

 

Yes you can, and no, it isn't a bad idea. That's exactly the way I would do it. There's more, or actually less, to it than what you're implying there though. What I mean is what you really want to do is just swap the carriers, not the ring gears too. The ring and pinion should stay in their original 3rds.

If you're careful you can re-use most, if not all, of the parts. It's the ring gear bolt locking plates that usually end up with tabs busted off. They're not too re-usable IOW. But if they get trashed, then use some locktite on the bolts when you put them back in.

Don't forget to keep carrier bearing races with the bearings they came with. Getting the ring gear off and back on the carriers is a little tricky. There's many odd ways of doing it, but I just lock the carrier in a vise and whack 'em off/on with brass drift pin and a reasonable size hammer. If you've got a press then that's what you should do. Then when you're done with that you just need to set the ring gear backlash and CBPL(carrier bearing preload)set.

The FSM has the rest of the details.
http://personal.utulsa.edu/~nathan-b...35differen.pdf

Those locking plates are PNC 41222 (part # 41222-35020).

 

Check out www.gearinstall.com this is very informative and very technical. You'll get to see the tools needed and critical measurements to measure.

 

He'll also need to re-set the blash and preload.. and whatnot.