Good advice on the accumulators + a couple of more things:

Check your battery hold down clamps. (Don't ask me how I know )

Also check your lower shock mount bushings. They can appear tight but will rattle when the car goes over bumps. It sounds like the whole back end of the car is coming loose.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles