cost of rear differential repair?

The book time to remove and rebuild a non-locking differential is 6.3 hrs and for a posi (locking differential) is 7.8 hours plus parts, And until its torn down its tough to tell exactly what parts are needed

You should go to "Harry's You pull It" in either Hazelton, Allentown, and I think maybe in Pittsburg to get a replacment differential for less thatn $100, then replace it. I can overhaul a differential for $360 plus parts, but you can buy a used good one for much less. It is not a complicated operation to change out. Differntial repairs are for the experieinced. Everything in there is totally mechanical, no mysteries. All you need is some basic tools, a feeler gauge, the replacement parts, and a torque wrench.