I bought a heater control valve from the parts store. It was for a mid 70's Dodge pickup. It is plastic, 1/4 turn ball valve that I control by attaching a choke cable from the panel to the valve. Works great.
Louie
The one in my pics came from Volvo const. equipment Loader, I have had them so long, and knew one day it would come in handy. I work on heavy equipment, The part number was not clear on package, but I will try and obtain it. There will be a Volvo equipment dealer near you. I think it might be L.B Smith possibly, anyway, hand operated, rugged, simple..1/4 turn from full on to full off.