I think that it was just a full 4.37 3rd diff from an 81, but the gouges were just in the thediff, not the carrier casing. I havnt ever heard any whining or griding noises, but Ive only driven the truck for a month and a half since I got it going.
I still havnt seen the front one yet. Hopefully its not the same way 
the part that is grooved is actually called the carrier.
