I'm using the 617 motor in my 39 Studebaker pickup. I am wondering what the function of the auxiliary pump is to the heater system. Will I need it in my pickup to get heat from the heater?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.