I believe that that heater is from a mid '40 thru mid '50s General Motors car or truck. Originally a heater would have only been mounted on the passenger side. 1947 and earlier Ford cars and trucks quite often had the heater mounted in the center of the firewall. Here is a photo of the heater in my '49 F4.

There is also another recirculating heater without the doors. Others may post a photo of that one.
Mark

 

The heater in my 48 F3 is the same as your F4
Ed
near Philadelphia

 

 

Denny , firstrider, here on the forum, restores those fresh air heaters. He would be able to help you with your heater.
Mark

 

Sent you a PM about getting your Magic Air heater situation squared away . Thanks Denny