Here's the deal. My first Mustang (2000 GT- 75,000 miles)- The right front lower speaker (mach 460) started to rattle bad. It was not blown, it just kept making this rattleing noise in the door panel. If i placed my hand over the speaker cover in the door panel it would stop. Naturally, I though it just needed pressure so i lined the door with pading... same problem continued.
I forgot about it and sold the car eventually.

Now I've owned my current Mustang for some time (2000 GT- 55k) and the same thing is happening again!!!

Has anyone else had this problem and how did you fix it?

 

try tightening the bolts that hold the speaker into the door check all bolts inside the door if that still doesnt work all i can say is dynamat