Hey guys - I have a 72 Challenger that I want install a flip top gas cap. I know it wasn't a factory option in 72, but I like the looks. Anyhow, I picked one up from Year One and I'm trying to figure out how the trim ring is retained. The flip top mounts right into the factory holes in the body surrounding the filler neck, and came with screws to retain it. The Trim ring has a small slot that matches a small slot in the cap, but no hardware/clip to connect them. I am an E body newbie, so that might be part of the problem here...Any help is greatly appreciated.

Thanks, Tony