Rear Door - lots of space in there. Use a couple $6 bottles of rubberized undercoating & some pillow batting to get good sound. On MY tracker, the way they keep the panels on are these little plastic "rivets". There's a center portion, and an outer ring that are flush with the surface of the panel. The way to get them off is to GENTLY push in the center hole with your favorite small tool. You'll end up breaking some 'cause they're old - but you can find replacements at junk yards & a lot of your better parts stores with the "Help" sections or misc bits sections.