Rear Differential Issues?
 

Ugh...where to begin. First off, I'd like to thank you in advance for any help that you may be able to provide. Let the saga begin...

I purchased an 01 Chevy Blazer in April. Before I purchased the truck, about 2 years ago, the transmission was rebuilt and the rear diff was repaired with new pinion bearing and seal. A few months ago, the rear diff started whining. I took it to the shop that the previous owner had it fixed at and they told me I had another 5 years before the rear end went out.

Then started the squeaking. We immediately attributed it to the U-joints and threw it up on a rack to fix them. It wasn't the U-joint, but the driveshaft had a good 1/2" play up and down and I had diff grease all over the underside of my truck. We pulled the plug to add more diff grease, and the darn thing was clean full! The shop replaced the pinion bearing and seal again, prefacing this fix with the fact that the whole rear end was going to need fixed before summer because of the metal shavings in the diff.

The whining has stopped, but the squeaking is still there, though quieter. Now I have a new noise that sounds like metal on metal when I turn right. I thought it was my brakes, but I just replaced them a few months ago. I can only attribute it to the rear diff.

***New symptom, has me stumped!*** Driving down the highway and all is well. I had to slow down for traffic. Once I get the truck below 55 mph and try to speed her back up, she sticks at 2,000 rpm and shakes. I can eventually get her back to driving normal after driving for a few minutes with the shaking. This was not a one time occurance either, it has done it several times in the past week.

What is wrong with my poor truck????? :(