Ok, so I have no system or anything in my car, and the noise definetley sounds like it is comming from the middle of the car. I think it is a external noise (it just really dosent sound like something rattling in the trunk). When I go over a bump, there is a rattle from the middle rear of the car. Also, if I am making a turn and I hit even a small bump the car will sway that way, almost like I am turning and hit a small patch of ice. Any ideas?

I read one post on here where it was the rear sway bar connectors, is that possible? How could I test it?

Its a 2000 MC SS, 112K miles

 

could just be your struts going out, do your own strut test by pushing each side(corner) of your car and test is bounce. it should only bounce a few times

 

If you have a rattle it sounds like a Mount to me. Those are just rubber in between 2 metal joints, and that rubber wears away and then you just hear the metal hitting the metal. I have it on my car also, but I'm not concerned about it right now until I can buy my new springs/struts/mounts and do it all at once.

When doing the bounce test, I would pop the trunk of your car, and push on the carpet on the inside of the trunk. I would never recommend someone just start pushing the outside of their car, or the spoiler to do a strut test.