The sound from the rear only occurs when I go over a speed hump/bump. It happens when shock is under compression and rebound.

It sounds just like the noise a drawbar will make, when you go over a bump when it fits kind of losely in the reciever of a class III hitch.

Noise is not from: hatchback, support joints, link bushings, drop links, frame bushings, anntenna motor, spare tire, tools, rear wiper tank, shock absorbers, parking brake.

Any ideas?