1971 Jaguar Series III E-Type Overrider Rubber Installation Question

I have a car in the shop which the customer brought in with reproduction overriders in a box. The rubber faces of the overriders are not attached, and have simple flat blades sticking out of them that pass through slots in the chrome piece. They are not drilled for nuts, and appear to be much too robust to bend without tearing the rubber. These are the first generation overriders for a 1971. The overriders are chrome bodies with a small rubber face that attaches to the front of the body. In the chrome body there's a square hole for the carriage bolt that attaches the unit to the bumper, and 2 slots 1/2" wide 3" apart that allow the metal blades embedded in the rubber to pass through. I don't have the ability here to post a photo.

Thanks for all the help you can provide.

Has anyone run into these before? Is there a clip or something missing that holds the rubbers in place on the overrider? Any help would be appreciated!