Ok while in reverse the rear end sounds like its coming out of the car sometimes. I think it might be a tooth missing on the rear. It does not make this noise in drive. Any ideas.

Rick

 

Try putting two bottles of GM's Positraction additive in the rear end. It might be the clutches sticking. If it does it when you are backing up in a straight line then probably something else.

 

If a tooth was missing, you'd hear it goin' forward too.
Do ya have a stick? Sometimes sound travels and it's kinda hard to tell where it's commin' from. Maybe your reverse idler gears are going, if it's a stick.
Although you did say when it's in drive it doesn't make the sound. So I guess ya have an automajic. In that case, try the additive. Check for a loose pinion gear too.

 

Mine made some real ugly noises before I gutted the rear suspension, found one bad U-joint on the driver's side half-shaft. Put it all back together with new bushings and a composit spring and it's smooth and quiet. Oh 'ya, all new U-joints too.

 

Since ya brought up suspension, the center support bushing can make a thump when yamove inreverse or forward. Forward is a more loud thump.

 

Thanks for the info. While I am changing the exhaust I will check the rear and support items.