A common problem with the 7.5s and also the 8.5s is the pinion shaft lock bolt. The bolt wears down then eventually shears off. Once that happens the cross pin is free to do what it wants, it hits the pinion gear every revolution carving deep grooves and leaving huge chunks of metal in the oil to be circulated by the ring and pinion. This is what i experienced. I opened the cover and the oil was silver, from all the metal shavings. My cross pin is so badly damaged i cant get it out, and the pinion shaft bolt sheared and is stuck in the carrier, and the carrier is bent up from the cross pin. Theoretically its a quick fix but in my case, my rear end is fried. You can see in the pics below what kind of damage it did.
Last edited by GM B-Body Forum on Mon Mar 10, 2014 11:00 pm; edited 2 times in total