So, after reading all the crap about the 66 C body having a distinct size grommet, I ordered one as I began to remove my tank. Evidently, and I am not smart enough to understand, but the cars with rear fuel fill at the bumper must have something different, unknown. So, after pulling mine, it measures about 2 7/8 OD and just over 2 inches ID. The one I got from a good supplier is 1/4 inch small. Mine has a cast number 2209472 on the back side. I have written the supplier, Sunday, and am wondering if I will have to use the OEM.....hmmm. This with further talk about the wrong materials, and check for gasoline accommodation, which I intend to do. Old cars.