On your deal the Ford solenoid will activate the Mopar solenoid so the current draw on the first solenoid is twice what it would be with one
AKA aside, use a 12 or 10 gauge wire to the Fort solenoid input battery side and a 12 or 14 gauge on the output side down to the Mopar solenoid with a 16 or 18 gauge trigger wire to the small terminal on the Ford solenoid
Thanks for the responses. When I get back over to work on it, I'm going to move the thing closer to the battery and use a bigger gauge wire just to keep the owner from losing his mind.
That is IF he doesn't work on it any more before I get there.
BTW, it's a Pontiac Cab, so only the one solenoid.