External voltage regulator wiring question
 

Any old wrench heads remember these, haha? Helping a friend wire up an old boat with one. I know internal regulation is WAAAYYY better, so I don't need that lecture. There are 4 leads, the first 2 on the left go to the alternator, the 3rd to constant voltage. Not sure on the 4th though (all the way to the right looking at it), does this one go to ignition switched power? BTW, engine is a 1962 292 straight 6, and the boat "is" offshore capable....... Thanks.

Convinced him to go to one wire, thanks for the help though......