help dianose rear end speed dependent noise
 

Hello all,
I pulled away from the gas pump the other day and heard a "chink". I thought i had run over something so i got out and took a look- nothing there. As i went down the road, things were fine until i was off the gas and coasting then i heard a knocking from the rear. Knowing that Ive had a torn CV boot for about 3 yrs i figured it had finally gone so i replaced the axle. Well that wasn't it, so now I'm thinking differential or drIve shaft u joints.

what am i looking for to properly diagnose this problem? The noise is speed dependent not rpm. Only happens when I'm coasting. Doesn't matter if I'm in or out of gear.

I'm going to check my diff oil when i get home as it does look like its been leaking.

I do have some play in my drIve shaft so i probably have to replace it I'm hoping that i dont need to replace the differential!

ALSO; i thought the outer CV joints were not rebuild-able because they are welded on. Not the case with mine. Its held on by a cir-clip. is that the norm?

Thanks for the help!

BUMP!
89 325is