Cat 3208's
If you go the route of alternator with the regulator, make sure its an 80 amp. Most are standard 50 amp. I had my alternators upgraded to 80 amp outputs when I had them rebuilt 3 yrs ago. It allows better battery charging when you are running without the gen on and you are useing alot of the 12 volt systems on the boat. Mike
Mike Lawrence 81 sportfish 33' shot'n'beer 
It turns out the relay I was looking for turned out to be a Cold Start Relay (Cat Part # 9G-8187). I replaced it and the voltage regulator (Cat Part # 6N-3161) on the starboard engine and ran it about 14 hours over Labor Day weekend with no problems. Think I'll do the port side next. Thanks everyone for your help!
Jeffrey R. Hughes M/V "Pescara" Cat 3208T's 1982 - 33' Bertram SF Santa Rosa Beach, FL