So have been having issues with my 91 since i put the new motor in about 8 months ago. just last week i flipped my drive shaft, and i noticed that my rear tires werent moving very easy at all. i had to force them around and the rear end made a squealling noise for about a half a turn. also i started to hear a whurring noise coming from the rear yesterday morning. my friend is a mechanic so i traded him a brown bag special for a rear end flush/fill and an oil change yesterday, and he said i was a little less than 1/2 quart low in the diff. so my next quess is that my rear brakes are stuck some. please help.