I discovered the same situation. I bought a reproduction assembly used the outer chrome trim ring , swapped few other parts , and used my original gas cap. I was unwilling to take the OE gas cap apart and instead reused it. I have more confidence in the fit and sealing power of the OE cap over the repro set up. It was cheaper to get the after market pop open gas cap assembly, $100, than to get my OE re chromed. Brian