Okay, I got the Blazer up on 4 jack stands and fired it up. The noise is definitely coming from the area of the differential behind the yoke that goes to the rear driveshaft. Along with the rubbing noise I could hear a high pitched squealing coming from in there as well -- a steel on steel sound. I'm half afraid to ask...what am I looking at here?

Oh yeah...another thing I noticed while it was in drive and up on 4 jack stands was the the drivers side rear wheel was spinning normally while the passenger side rear was not moving at all to very slowly at times. Does this have to do with limited slip or am I looking at another problem?

 

Sounds like you are in need of a rebuild. Check your fluid level. Check for abnormal play in your pinion[input yoke] Pull the diff cover look for metal shavings. more than likely your are going to be rebuilding or getting a junk yard replacement. If you go the later route make sure you are getting a rear end with the SAME GEAR RATIO if your truck is 4wd. If you dont you can say goodbye to your transfer case the first time you put it in 4 wheel. As far as one wheel spinning that is normal for a "open" differential. That is what happens when a truck loses traction in one wheel. All power goes to that wheel because it is the path of least resistence. That is why people put a locker or limited slip to get equal power to each wheel.

 

Today is a good day! The pinion bearing was fine, no play. So was the rest of the rear end. However, I did find out what was making the noise. It was the rear universal on the rear driveshaft that was doing it because the 'clips' weren't installed. I know, I'm a dumb azz...lol. Now my '99 Blazer rides like new! WOOOOO HOOOOOO!