Thanks..Its weird the truck is a 54 -3100 with 56-7 engine. The heater motor on the Harrison delux heater is12 volt but the wires from the motor go out through the rear of the motor. I have never seen that. In fact I have to push the wires back through the firewall into the cab to get to my rheostat switch. I guess your right what difference would it make on what hose the shut off valve is installed on. During the months we don't use the heater I always open the heater hose valve and run with the heater on. .....
Thanks, Steve