Running a positive ground regulator on a negative ground system doesn't create any catastrophic failures- - - -it just doesn't last as long because of the potential for metal transfer from one vibrating point to the other on the voltage control unit. The current regulator and cutout relay won't be affected either way. At least that's what a Delco-Remy instructor in a seminar I attended back in the early 1960's told us, and 50-something years of servicing DC electrical systems has proved to me that it's true.

"Your mileage may vary"!

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!