My 93 GMC has 261000 miles on it and had developed a knocking noise, first thought it was a U joint, then wheel brg. Sad to say 2 teeth out of ring gear and only found 1 in bottom of case. Spent morning at salvage yard. Spent afternoon in shop getting ready to change out the hole differential. I have put 3 ring and pinions in it and had one put in long ago. Its always the same So this time I'll change the hole thing. I figure there must be something wrong with the case. There is still hardly no lash in it, but I just don't feel like going through the gear changing. Anyone else have this problem??? its just a 10 bolt GM has them in every thing.