I am noticing a *slight* squeaking when I go over bumps coming from the rear of the car. Back there I have Bilstein HD's that were installed not that long ago. Is it possible they are already blown?

 

The shocks aren't blown. Just about every F-body has that sound. It's can be one of a number of things. The shock could have been installed wrong, the LCA bushings could need replacing, etc. Check all the bushings.

 

Above post is true, all F-Bodies get it. Just one of those squeaks/rattles that come with age.

 

yup, i've had that same squeak for a while now. i noticed it on the stock shocks, and it was still there when i put bilsteins in. so that rules out the shocks. just turn up the stereo...