Does anyone know if the 65 alternator is different from a 66? I installed a 289 from a '66 mustang into my '65, and the alternator did not work, so I bought a replacement (for a '66) and installed it, still nothing. Then I installed the original alternator off of my '65 289 and it worked. So I have a new alternator and I can't use it. Is there a difference between the two or could I really have gotten a new alternator that wasn't any good? Thanks.

 

there are some slight wiring differences between a 65 and a 66. Your problem may be with the wiring and not the alternator itself.

Study these two diagrams and determine how you are wired
http://www.midnightdsigns.com/james/...g%20Gauges.htm

 

66 and later alternators had an internal radio noise suppressor, the 65 did not. They are, however, interchangeable.

 

Thanks guys.