rear disc from grand cherokee on a 8 3/4

arch,
Im sorry for not seeing your post, I called and talked to the people at the yard first and asked on this forum, The amount of work necessary to make the swap is not worth the effort because what they have is essentially an 8 1/4" rear. which is why the swap is a bolt on for the 8 1/4. However the entire suspension built around the jeep rear end is completely different from our A bodies.
Andrew