Thanks Guys,
Turned out to be voltage regulator!

When the gen light is on when ignition off, and off when ignition on, it is the cut out points in the regulator stuck closed. You must have driven a ways with the generator not working, which would cause current to flow backwards thru those cut out points. That may have made them stick. If you repair the generator you need to clean/file the cutout points or replace the regulator. Replacement is what we always did back when I worked at the dealer, but we just wanted to prevent recurring problems. Make your own choice.



Tom from the chiggerfarm located in the beautiful Heart of Central Texas

When you cannot dazzle others with your brilliance, baffle them with bullcorn!

I'll bet the brushes and commutator just needs cleaning; but I'd change them anyway. Back in the day I did many just using a little sand paper and rubbing alcohol. Not difficult if you have a shop manual and some hand tools. Today I wear light weight gloves but not years ago. Good luck

56 Vic, B'Ville 200 MPH Club Member, So Cal.

gen, needs new brushes, DYI for oess than $10.00

Had a similar experience and it turned out to be an internal problem with the generator. If you have a good rebuilder in your area bring them both the generator and the regulator for bench testing. While you are at it have a good look at your charging system wiring harness to be sure that there are no issues there such as broken or burned / bare wires.

Pete

Hey guys, not really electrical wiz more mechanical so here goes. It's about my generator or voltage regulator. Last night going to a cruise in my 57 Ford Fairlane my Gen light came on for a few minutes then went out. Later coming home at highway speeds the Gen light came on and stayed on my volt gauge dropped to 12V obvious not charging. After a few miles light went out then volt gauge went up to about 14V charging I assume. Now here's the issue after I shut the car OFF the Gen light came on! Then I turned the key back on and light went out? Turned key OFF again and light came back on! Then volt gauge pinned at Neg volt meaning definite draw. When I removed battery cable I got spark from it defiantly a heavy draw / short. So would I be best at assuming Generator bad or look at voltage regulator? I don't want to connect battery and start car if at all possible but might have to to test what the Generators putting out if anything for starters. Any ideas what I should test and how would be helpful. 
Thanks
Mikey Baby Blue 57