Noisy Chrylser Concorde

We have a 2003 Concorde which has a serious rattle sound when you go over bumps. We have had the brakes,struts,tires checked at Pep Boys and the dealer. They can find nothing wrong. Any suggestions?

Has anyome checked for a loose exhast pipe or catalytic converter shield???

It is the rear right side. Have checked everything I can think of including the spare to see if it was loose. I got under the car with a rubber mallet to bang on everything and nothing seems loose.