If these are on your 65 Cuda, they are held on by the wire spring clips for all but the back hole. The back hole near the taillight should have a nut threaded onto the stem of the last clip. Stick your head in the trunk and look up along the top of the Qtr. and get a visual of the clips. Take the nut off first, check to make sure there are no other clips with the nut, then go up top and pop up the trim with a screwdriver or trim tool, prying up slightly to see the wire of the spring clip and protecting the paint of course. They will pop out of the hole easier if you pry them up right at the clip, or you can go back underneath and squeeze the clip with some pliers and push it up partway through the hole. The spears slide onto a tang on the taillight housing, so once you get them pried up you should be able to slide them forward to slide them off the tang. Good luck with your project. Geof
