Most wrecking yards nowadays have service shops. They will have the diff and will offer warranty as well. I have gone this route on the troublesome items in the past. Also they are quite reasonable, as nobody can remove parts as fast as these guys.
each rearend is esentially the same but the suspensions are very different. you CAN swap them out. but they will not be bolt on. you have to cut tabs and perches off of the Cherokee rear and replace...
If it is like the Country model, carefully pry off the black grills over the speakers. Be careful not to bend the metal prongs on the edges of the grill. Then the speaker is exposed and you will find...
its not the easiest alt to change. take out the battery & box, loosen pwr steeing pump & loosen/remove the belt, reomve wires on alt(including the battery cause its to close quarters and you'll bump...