I recently removed the fold down rear seat and trim panels from my 70 Boss 302, that was built at Dearborn, April 20, 1970. I expected to find the trap door trim panels riveted in place like every other set I've seen, but instead found them secured with small round headed phillips screws. I didn't think enough of it at the time to photograph the screws from the inside, but i do have photos of the self tapping tip of the threaded screws visible from inside the trunk.