maybe its my time for lsd. iv got a bad grinding noise coming from what i believe to be the trans. no change with rpm or clutch. only wheel speed. all the gears feel fine. i can hear the noise best when coasting at 30 or 40 in neutral and all the way down to when i stop. i can still hear it at higher speeds but is drowned out a lot by wind tire noise and the motor. dont think its the wheel bearing. doesnt change while im turning and doesnt sound like other wheel bearings iv heard go bad. it sounds like metal to metal grind...grind...grind...grind...ect. all started when my friend had the bright idea to polish his RS's while they were mounted to my car. we lifted up one side of the car and spun the wheel in gear with the other wheel on the ground while he was sanding. nothing at first, but after a little bit started to hear a faint grinding noise. slowly the noise got louder and louder till i stopped. now that iv been driving on it i feel like its slowly getting worse. iv stopped driving on it and hopefully tomorrow il get it up on jacks and put it in gear to see if it really is coming from the trans. sucks because i just got my trans back in for the 2nd time just two weeks ago and not really looking forward to doing another tear down this soon. cant find much info on other people with bad diffs. anyone here have any experience with a bad diff or know someone who has?
dont worry im gonna post this on stock issues/problems but i figure i wrote lsd so thats a "mod"

 

Sounds like it could be the diff. Have it torn down and looked at before it lets loose. I had a spider gear in my open diff shatter and knock multiple holes in my trans. The total cost to change just a diff and clutch is much cheaper than those two items plus the cost of a new trans.

Quick question Why didn't you jack up both wheels?

 

What you describe could be the differential carrier bearings.