Marcello asked me to call Concours @ 800-722-0009. I spoke with Jay. He said the alt he sells IS a three-wire, 60-amp, GM type. He also said he knows he has brackets for a Y-Block but isn't sure about the FE.
If you are retrofitting to an alternator, get one that is big enough to run an electric fan. Some day you may install an electric fan or an electric water pump, etc.
Modern cars all have (electric fans and) alternators over 100-amps so I know bone yards are throwing them away every day.
Overcurrent protection is a "must have" on all alternators because alts use diodes that can short (at any time). It's like wearing seat belts... you may never need them but if you do, you want the best ones made. Fusible links work just fine, but are a little harder to find/replace than a fuse.
I really love to see all T-birds with modern alternators, and I don't care what brand you use. I don't like the one-wire type because it doesn't charge until rpm's go over 1,500, it gives no indication if you threw a belt, and it has NO way of using the GEN or ALT light. (Notice that none of the OEM's use it.)
That third little wire is a 'sense' wire and it directly connects to your GEN light wire. It senses that your key is on, it shines your GEN light until the engine runs, and it regulates your charging voltage. In short, it just works the way you would expect it should. - Dave