George, we have been experiencing this problem in Chev pickups in the rear ends. The bearings on either side of the crown gear have the same problem. I took one of these apart earlier this summer and found that whoever supplies these rear differentials seem to be using offshore bearings- no number, no company name. They even look cheap. The same day I took the unit in for repair, the diff shop had 3 more with the same problem. The chap there told me that once this happens, the cone spins on the carrier and renders it a piece of junk. It is not thick enough to repair (this is the area where the bearing is pressed on). Funny thing though, they had Timken bearings on the pinion shaft! This truck was relatively new-just far enough off warranty. What I'd like to know, is where in the hell is the quality control people? Seems that they are exchanging quality for quantity! This is not a cheap fix either, $687.00 at the diff shop, and $1700.00 at the dealer.