The "deluxe" Air Flow or Fresh Air heaters are quite nice and look more impressive than the Recirculating heater. They might be better at defrosting the windshield, because they do not have to recirculate the interior air. A
replacement heater core is available for the 47-52 units.
Nonetheless, the recirculating heater is quite good. I have used one in a 1954 pickup on a 150 mile night-trip at 8 degrees F. I had just bought the truck and all of the window seals were bad/leaky. I was able to drive without gloves, with my coat unbuttoned. I have also used this style heater on long cold, rainy trips and the defrosting/defogging worked fine. The recirculating heater is easier to install and to plumb, and it has fewer parts to go bad. However,
a replacement heater core is more expensive and requires professional/skilled installation.
Post a Want Ad in the Swap Meet for either/both heaters.