@spitfire
all this thread shows is a bunch of mounts with the "gaps" filled with what we call black silicone caulking which offer s bit more support to the mounts (common sense idea, but it makes the mounts stiffer)
As for the urethane bushes,... yes it can be done, but it'd take a bit of research into making/finding the ideal mix for our conditions. all you'd need is to make a die and then pour the urethane and let it cure.
I'll be looking into this when my beetle is done, will pass on whatever i find out to you as well.