Eating Up Voltage Regulators

[41SupDelux]

Evening, gentleman,

1941 Ford Super Deluxe

I have a problem. I mean, I have a lot of problems, but specifically, with voltage regulators. I have gone through four voltage regulators. One extra that came with the car, two Echlin brand (Made in the U.S.A) and one Duralast (also U.S.A. made). I have a 6v positive ground system. I don't know what it is, but my regulators keep going bad, with one common issue being the contacts getting welded together. I have noticed it does seem to commonly occur at night, when I'm running my headlights. It'll work for a time and then bam - it stops charging and then the battery begins to drain, while driving and then once I've turned the car off. I've gone through the normal polarizing procedure, though probably not necessary as I'm not changing the generators out. Both generators I've tried are pretty old and I have no way to tell how old they are or if they were rebuilt; both came with the car. Am I using the wrong regulators? Each one has been generic for positive ground or negative ground systems. At this point, my next action would be replacing both the generator (or getting it rebuilt) along with the voltage regulator; essentially, starting over. All tips, links, and recommended equipment is appreciated.