Rear End... Problems???

[stng87]

This is a really crappy. I noticed a leak from the diff this morning. It wasn't coming from the seal though, it was coming out of a pin-size hole in the inspection cover right behind where the the ring gear sits. SO I am thinking that the ging gear is for some reason hitting the inside of the cover. I thought that maybe the cap bolts on the carrier housing were loose and letting the carrier housing shoot back on accelleration and contact the cover. So I took it off and found that the gear was indeed hitting the cover and did cause the hole. In fact it looks like it has been doing so for a long time and evidently just recently finally made a tiny hole through the cover. but here's whats weird. The cap bolts are perfect and everything seems to be in order.
Now the gear IS a 4.10 so is a tad thicker, but even considering that, I have never heard of the carrier housing flexing enough to contact the stock cover... any suggestions?