Mr Google is my friend...
http://www.mfgsupply.com/m/c/MM-101C.html?id=8v7665if in my case..
http://www.mfgsupply.com/SnowMounts....on_id=8v7665if for others with different spacing requirements.
A bolt through a rubber bushing, end link or piece of tire still has a metal to metal link, hence the through bolt. I wanted 100% isolation as these low cost units have.. I'll buy 4 and squirrel them away for future isolator failures.