I figure I ought to report back my final solution to this problem. Most of the t'bird parts houses only show a Bell Housing to Starter Seal for the '58-'62 model years (Mac's, TBird HQ, etc). But Pat Wilson's Thunderbird shows the same seal for '58-'64. I called them and asked why they listed the part differently. Their explanation is that it is the same engine, starter and bell housing (at least after '62). Why wouldn't it be needed?
So, I got the seal and installed it. The seal is basically a metal plate encased in rubber. It shims the starter out about 1/8" when tightened down. It is a bear to install.
But it worked!
