axle 101

Probably time for some axle bearings.

Try changing the fluid first and if that doesnt work, you need to invest in a rear end rebuild. Change your gears while your in there also.

Sounds like axle bearings to me....Never had a rear go bad, one in the front though...
Jack the rear in the air an inch or so...grab the tire and do the up/down..side/side movement...if the axle bearing is shot, you'll feel the play...as there should be nil....
If you turn your own wrenchs its not a hard job....gotta remove the dif cover to drain the fluid and pull the C-clips out as the axles have to come out to change that bearing...The bearings and axle seals are cheap money..
Oh dude.... that means the dreaded ABS sensors have to be removed.... thats prolly the worse part of the job as the mothers like to break...they're plastic...