John,
you're more likely to find one from a 64 to 68 big block car (pass & corvette)if you're looking for a used one. the drivers side are usually torn up.
I looked for a long time to find a match for the one I had & finally got one.
http://cgi.ebay.com/ebaymotors/ws/eB...m=140203140089
It's basically a big block of rubber.
Good luck