The heater that came in my 53 half ton is what I'm told is a fresh air deluxe heater. It has a door over the core that is linked to a smaller door on the front, that open to allow outside air in. It's pretty rough shape, and it turned out to have a core leak that my radiator guy says is not repairable. So I bought another similar heater hoping that the core will be OK. This second heater looks like the first one except it doesn't have the 2 hinged doors. It looks the same otherwise, and is open on the core end where it mounts over the rectangular hole in the inner cowl. So, it appears to me to be a fresh air heater, except with no way to actually cutoff the fresh air. Both heaters are made by Harrison, and both look the same except the door issue. So which would be correct for my truck, and what truck or car would the other one be for? At first I thought they were identical until dis assembly.
