To be brief - the RX-7 transmission crossmember has bushings, because of course it does. These are not replaceable and otherwise unavailable - one of mine was dryrotted and completely failed. The solution? 80A urethane to fill all the spaces and encapsulate the remainder of the bushing body.
Due to the design of the bushing (which I won’t get into, but basically it needs to be bonded to the outer sleeve, which is shorter than the inner) an off-the-shelf universal flange bushing wouldn’t do it. I picked up some liquid urethane (in 2 parts) from McMaster-Carr after work last week, formed it up, and poured the above bushing. Once cured, a razor squared up the face (wasn’t level and my mold wasn’t very good, or even round, really) - turned out pretty well I think.
I got it and a new Mazda “competition” transmission mount bolted up tonight, as well as re-installing the heat shields I had to take out to remove the cossmember to remove the mount.
Hopefully tomorrow I’ll get the new motor mounts (came today) installed and complete another step in the winter maintenance plan.