1951 Heater

[51shoeboxer]

My recently purchased 1951 convertible has only two hoses to the heater, rather than the four that I see in photos of other 1951 Fords. There are only two brass tubes, rather than four sticking out of the firewall. Unfortunately, my heater is not hooked up, as the outlet on the passenger head is plumbed directly to the passenger water pump; the two brass tubes on the firewall are just plumbed to each other. I want to have a functional heater, so I need to know if Ford made two different heaters: one with two hoses, and another with four hoses. Thanks for your help.