I think that is what is going on. I think CumminsDoofus ment to use a normally open swich that closes with oil pressure, sending power to the alternator. He must be adding a switch in somewhere. If I recall correctly there are three pins on the stock (at least on my '89 engine) Cummins switch. One has a variable resistance to ground that changes with the oil pressure that I tied into the Ford wire that went to the gasser sending unit. The other two were on a normally closed switch that opens with oil pressure. I assume these hooked to a idot light in the Dodge so the light would come on with no oil pressure. I have had zero problems with my alternator wiring it like is shown in the picture. For my "hot" wire from the ignition switch I used the wire that powered the Ford Duraspark ignition module.
AWard. Did you get yours working? Sorry I wasn't any help, I never saw that you were having problems untill just now.