Not sure what vehicle you've got, but check your sway bar bushings. My SVT started making hellatious noises almost overnite. Any time the rear suspension moved more than a tad. Finally got time to put the rear end up on my ramps and started bouncing the back end up and down while under the car. The sway bar bushings were the culprit. Pulled them out and greased them and now all is back to normal.
