I don't know what heater you are referring to but for these trucks, the heater is usually either the "fresh air" heater or the "recirculating" heater. Either one has a duct outlet for the defrost and tubes connect them to the defrost ducts.


1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed


My Chevy Master 4 Door is on the Road!