The voltage regulator usually has a voltage stamping on the base somewhere. If it's a Delco unit and it isn't marked with a voltage rating, post the part number and one of us with a parts manual or some service bulletins should be able to tell you which voltage rating it has. It's a little more difficult to identify a generator with the tag missing.
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!