Here are some photos of the heater in question:
As far as I can tell (by looking at the install manual) this heater is the basis for the Harrison DELUX model, also. I see this heater is a LOT of CJ2A and CJ3 photos.
I am trying to determine when this unit started production (the manual I have is 1944).
And if the boss, the small raised circle in the lower right front corner, just above the flat to hump transition, is its own model.
This model is different from the CJ unit, the mounting flanges, bolts, and supply/return tubes are different.
I am of the opinion that the 1944 model (used by GM in CCKWs and other larger trucks... but not the Chevy 1.5 ton) is 'slick sided' (ie the raised boss is a post war modification added to the dies for the DELUX model which had defrosters and baffle controls).
