There is a Air Flow / Recirculating heater for sale over in the
eBay and Craiglists Links forum pretty good price for $100 bucks..
There were really three heaters that were widely used in Advance Design Trucks.
(#1) Recirculating (only) round type heater 1947-55 1st series (round heater core) defrost to floor air control was done manually using a lever located on the heater box. A three speed fan motor switch was used.
(#2) 1947-52 Air flow non-recirculating (no doors) (rectangular heater core) The air flow only non-recirculating heater has a cable control, that opens or closes a door, for defrost or floor heat. A three speed fan motor switch was used.
Picture of heaters #1 & #2 (Another quality photo from Brad Allen)
(#3) 1953-55 1st series Air Flow / Recirculating (with doors) (rectangular heater core, same as # 2) The air flow / recirculating heater has a cable control, that opens or closes doors, to recirculate cabin air or bring in and heat outside air. (keeps windows from fogging up. The defrost to floor air control was done manually using a lever located on the heater box. A two speed fan motor switch was used. This heater was also considered "The Deluxe model"
Picture of heater #3 (Another quality photo from Brad Allen) x2
Here is the air flow heater (#2) (non-recalculating model)
Installation instructions Pages 36 to 39The Air flow non-recirculating (no doors) and the Air Flow / Recirculating (with doors) heaters, are virtually the same and mount to the kick panel the same way.
There is a in cab temperature control valve used on heaters #2 & #3
