Here you go... McMaster-Carr Hard 80A Polyurethane - Product # 8644K11

Edit: If you are going to do this by hand, I recommend using a large vise at the very least to secure the mount while drilling. Brace yourself and your drill to go through the rubber around the center like my mill and use a 1/4" to 3/8" bit. You can make multiple holes around the perimeter of the center portion of the mount and then cut the remaining rubber with a VERY sharp wood chisel and hammer. Also, trimming out the excess rubber from the outer housing with a sharp wood chisel is preferred to trying to cut with a box or utility knife. This would be about the safest route I can think of. I trimmed up the center piece with a utility knife but the piece was held firmly in a large vice for safety. Don't forget unbroken mounts are full of about a cup of fluid, if you want to drain them first, drill only two holes to start like I did. (One for drain, one for air.)

Whomever wants the mounts, and jigs for their project need only pipe up and/or PM me. I will be putting these back in next week. Cheers!