HELP...serpentine to isolation block

I have an 85 full size blazer...completely custom. When I bought the truck it ran like a truck. The only problem I've had is the alternator. The berrings seized. Ok, got it fixed...now I can't seem to get it right, the batteries keep draining. The alternator is digital...can't remember exactly what he said, something like a 4 pin, 1 wire regulator digital. Anyway the only thing I know for sure is it was rebuilt and the regulator was bypassed inside...ANY ideas of what is going on here (The batteries were tested)