1954 GMC truck heater

I am looking for pics of what this heater looks like, and how it installs in the truck. I purchased a heater from a gentleman, but the year of vehicle it came from was not said. I found a guy on the internet who was restoring a 1950 Chevy truck, and he had pics of his heater (which looks like the one I purchased). If this is the correct heater, I don't see how it installs correctly. Any help would be greatly appreciated.

This looks like the one I purchased.

 

mounts to the kick panel.then run duct for defrost.there is a heater core inside the access in the kick panel.if not,install one.

 

What hotrod said plus the fan motor sticks through the firewall slightly.