Thanks - Bill. The Ranco valve is more like flow adjusted than an on/off valve. I think I can put a valve on the lower hose in the middle of the inner fender and then run a vent style pull cable to the bottom of the dash. This will make it controllable from inside. I did this on my 56 pickup with standard heater and deluxe controls. Hooked it to Temp arm (travel not enough). So when the control is off the valve if off but when all the way on the valve is 60% on (enough to heat the cab.).