I bought a set of re pop door panels for my 69 Mach 1. I was getting ready to install the pull cups when I noticed that there is no internal plastic frame like on the originals, just foam. Without that frame being in there is nothing to rivet the cup to. I'm curious as to how others have handled this problem. I can't think of anything that will hold up over time to keep them secured. Any suggestions? As always, thanks in advance.