The other day I was driving my 91 coupe and when I let off the gas this seriously ugly noise started. It sounds as if the rearend is coming out. But when I'm on the gas even lightly, theres no noise. Let off the gas and unload the rearend, the noise starts. I put it on stands and in gear and tried laying beside the car with my foot operating the clutch to duplicate the sound. I got it happen to a small degree but when it would do it the left rear tire would jump a little. The axles seem fine, the driveshaft seems fine. I first thought the driveshaft was loose, but its not. Anyone ever experience this?

 

Need some info about the car first my friend.

Do you know how many miles are on the diff since the last rebuild(if it had one done) or fluid change?

Is the diff. a LSD or open?

 

The diff is factory, 128k, lsd

 

Try changing the fluid in it with Royal Purple gear oil. I hear its suppose to cut down on the noise of trannys and rear ends. Don't forget to put in the LSD additive either.

Thats about as much as I know about rear ends for these cars. Maybe someone else can chime in and help you out.

 

I had my passenger rear hub go out on me about 2 years ago, did about the same thing you are talking about.