Whoa Gus, all the three replacement supports that I've gotten
from Classic Parts of America have had the steel bushings
potted or vulcanized into the rubber. I don't see how the mount
would work properly if it weren't bolted up solid to the front
plate on the engine.
And on that curved lip of the top plate, we did a lot of
searching on that one as Lonnie mentioned. This is the way the
mount came apart on my '50, 216 and I did talk to the people
that bought the truck new and maintained it over the years.
They had never changed the mounts, and I believe them cuz the
front and rear of the engine were simply sitting metal to metal
in a mass of JELLY that was once rubber.
http://www.pbase.com/dennygraham/image/128165791 Denny Graham
Sandwich, IL