[elav]

That panel holds the rear defrost plug on the top surface. Take a look and if you can't see the plug, it probably fell down and is banging around. That panel has a screw in the carpet and a snap and hook. I have an extra panel I can take a pic of if you want. I also had a rattle in a similar place. It turned out to be my convertible top transmission arms. One of the arms was missing a rubber grommet and the arm would bounce a little over bumps and rattle.