I actually did what you need. I used the "plates" from the original, found two "hockey puck" rubber pieces that had a center hole and the right thickness. You can also use a rectangular block. I don't think I could find one, can't remember. Anyway I put new bolts down thru the horseshoe mount, thru the plate, thru the rubber, thru the plate, thru the frame piece and used washers and nuts. (approximate method from memory). As long as the durometer is correct, it's a done deal. If you need to make new flat plates, make new flat plates.
