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