sfd4

When ever I hit a bump or several bumps I hear a loud clunking sound in passenger side. The sound comes from the area of rear cabin area on the passender side of the vehicle. Almot sounds like something within the vehicle hitting the inside of the body or the interior plastic cowling from the 2nd row seating towards the rear hatch. I took the 2nd row seat area passenger door molding off and the soeaker is tight as is the window mechanism. I have also taken out the 3rd row seat, checked for any loose connections on the 2nd row seat. I also checked under the truck and everything feels tight. The spare tire is tight, the tire jack is tight. I am thinking that may be something connected to the rear seating air conditoner system which would be on passenger side of the truck near the rear. I cannot figure out how to remove the plastic rear interior paneling on the passenger side of the rear of the cabin. Any ideas out there. It is very loud and disturbing as is only when hitting bumps in the road.