Rear Lockers
If you're looking at the available rear lockers out there, another one to consider is a "No-Slip" by Powertrax. This is a very much improved version of their proven Lock Right. If you are not familar with their products, the locker unit fits into the existing differential case. The only glitch on our Dana 80's is that the ring gear must be removed to pull out the cross shaft. So, you gotta pull the carrier out, which is no big deal at all. Especially compared to setting up a whole new unit.
I recently put one in my 96 2500, probably about a two to three hour job start to finish. BUT, driving a locker is definitely different than a limited slip. they do make a little popping noise when they load and unload. Not a bad thing, you just know it's there.
When I bought mine, it took a LOT of phone calls to find a place with some in stock. The best place and also the cheapest is Reider Racing in Michigan. Under $500 Fed Ex delivered in two days. Ask for Barney, outstanding customer service AND knowledge, not just a phone answering salesman.
More info at Powertrax.com or ReiderRacing.com