The rubber separated in my 1985 300D years ago. I wrapped it w/ steel wire, which worked fine. I doubt the rubber helps much in decoupling engine vibrations from the fuel pedal, which I assume is its purpose. I eventually replaced w/ a junkyard one, plus grabbed a spare later. One car I pulled one from was an earlier ~1970's M-B so appears many cars used that basic part. My W123's have 2 holes on the firewall to install it, only one of which fits. I expect the other mounting hole is for gas W123's.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans