This happened tonight on my way to work, the clunk was on a decel and the jet whine started at about 60-70mph. I just got back from a food run and no clunk or whine, I have heard this whine in my 83GSL when I last drove it. Sounds like a drive line and ???? rearend or LSD? The tranny make noise since I owned the car and 5th gear is never used due to the nasty sound it makes.
The jet whine sound is what I really am clueless about.
This is my drift car/DD and I do alot of clutch kick so I'm not surprised by this, just wanting a 2nd opinion. I have a spare 3rd member/LSD and tranny on the shop floor.

 

Try jacking the rear up, put it in neatral and rotate one wheel, if both turn the same way you still have LSD, some anyway. Then rock it back and forward looking for slack in the rear universal, axles etc.

Might be your tranny going out but this will eliminate some easier to find issues.

 

I never thought of the rocking part to check for slack, thanks!

 

Make sure you put jack stands under it before you rock on the car

 

Come on, you are such a party pooper!

 

mine whines sometimes during decceleration but it's an open diff and i never thought anything of it before now

 

I'd hate to be waiting for you to reply with you head under a differential.....

I think my tranny is going out also, crunches changing down from third to second and whines in fifth.