<VV> Gen/fan light issues

[Al London]

This is a 65 Monza issue. To begin with, the speedo didn't work (separate
issue) so I got a used cluster and swapped the whole thing. All was well
until the gen/fan light stayed on when the key was off. I could hear the
voltage regulator de-energize when I disconnected the battery so I assumed,
along with group consensus, that was the issue. I replaced the voltage
regulator and solved the light staying on problem but now it won't come on
at all when I turn the key on except if it is to the ACC position. I have
tried putting the old cluster back in and it does the same thing. I have
tried another new voltage regulator no change. The pressure/temp light
works normally. Both wires to the Gen/Fan light show hot on my test lamp so
it would seem that something has to go to ground that isn't. Thinking maybe
a new ignition switch? a stuck relay? bad alternator or diode? BTW the
alternator shows 13.8 while running.  I really don't want to just throw
money at it until I have changed everything it could possibly be. Any
suggestions are greatly appreciated. Tearing my hair out (I don't have too
much to spare!) and also running out of ideas.

Al