which heater? Commonly in BC I see the 'standard' or 'deluxe' being what they came from factory with. Both were options and BC trucks usually had one or the other. If your cab came from elsewhere it could have had nothing or any one of many aftermarket heaters.
The standard heater was round, mounted direct to firewall and the copper pipes protruded through the firewall. From engine side there was a large round blanking plate
The deluxe was larger, connected to the passenger side kick panel to get fresh air from exterior louvers. The heater was spaced off the firewall on inside, the copper pipe on heater core connected with short sections of heater hose to a valve that protruded through firewall. The end of the fan motor protruded through firewall where the standard heater had a blanking plate
