When I needeed to replace similar resilient mounts on a ML7 motor, I found a rubber supply house in Slough who made some replacements to fit.

An alternative is to convert the motor to solid mount form by replacing the through studs with longer ones and making a new U shape frame to pick up on the through studs. This frame can be mounted to a suitable carrier via your choice of available mounts.

I tend to make my own using thick wall rubber tube (usually old style car heater hose) forced into appropriate size holes. For flat mounts 1/2 to 1 inch plywood with suitable excess material poking through so it compresses into a mushroom head between wood and mount aided by large washers on the other side is effective. Needs a good mushroom head so that things can't fall out. For hinge style mounts use metal tube made a little shorter than the rubber with suitable ears welded on. Pushing the rubber into anything much over 1 1/2 inches long becomes hard though. Small adjustments to pin diameter control the stiffness. Anything from heave hard to (almost) free moving without shake is possible.

Clive