Mexican Valiant voltage regulator

First thing is "what do you have" for an alternator?

Someone may have adapted something.......Japanese, etc.

Some off- brand stuff used Motorola alternators, which were a nightmare. But most other alternators boil down to a pair of brushes and a field winding, and one end of the field may or may not be grounded.

"In their day" you could use a 60-69 regulator on just-about-anything, from tractors to fork lifts to darn near anything........You hook it to a good ground, one wire to "switched" ignition power, and the other to a field terminal. The other field brush must be grounded