I found it under the seat of our 1953 Chevrolet pickup, which we bought a few months ago. The pickup has a recirculator heater. I tested the motor using a voltage reducer (just in case) but it did not work. So now I am not sure whether to buy a 6 or 12 volt motor to use with this switch. By the way, this switch has "Heater" written on the knob. I think I have seen similar switches under the dash of some of the AD pickups on these forums.
Thanks.