An alternate version of J.'s, look for the outter "ring" of the spare tire cover from a '33 to '36 Ford (V8er's hate it if you call it a "Continental kit"). If you look on ebay, your search perameter will work better that way too.

Here's an example of one on ebay right now: http://cgi.ebay.com/ebaymotors/ws/eB...tem=2437784120
Although, it doesn't look like a Ford piece to me, it will give you the idea.