BigDually and Richard's truck utilize the Delco Hypower system which is the predecessor to the Bosch Hydromax. There were 2 different style motors and I have seen both styles on the Hypower and Hydromax systems. I think it all depends on the specific vehicle it was going in.
1 style has just the positive wire going to it and is grounded through the body to the chassis and the other has 2 wires, positive and ground.
They both have the same mounting holes, same inlet and outlet holes and same o ring seals. So in theory they should swap back and forth.
Somebody should buy that replacement pump and report back to us
