The GM Harrison Division made heaters for Chevrolet trucks and passenger cars. They were not installed at the factory ... Chevrolet dealers installed them. They were relatively expensive. The list price of the AirFlow heater on my '54 3104 was $64.87 - the most expensive option on the truck.
https://drive.google.com/file/d/0BxisXBEpc-IWdHZCYVFnRnl4bUU/view?usp=sharing

The switch was probably a three position toggle switch that came with the heater. Holes were predrilled in the dash for the switch and heater controls.

Switches in working order are getting rare. I installed a non-working original switch on my dash, then hid a modern rotary switch inside the dash away from wiring and paint because it gets very hot.

Heaters were also made by aftermarket manufacturers.

Your questions are answered in the 1951 Chevrolet Accessories Installation Manual:

> (p. 36) 986104 HEATER & DEFROSTER - Air Flow, Truck
http://chevy.oldcarmanualproject.com/accessories/1951am/51aim36.htm

> (p.39) 986554 HEATER & DEFROSTER - Recirculating, Truck
http://chevy.oldcarmanualproject.com/accessories/1951am/51aim39.htm

- Lonnie

- Lonnie
My '54 3104
Photos that I have shared on Stovebolt via PhotoBucket are no longer available. Please contact me if you want a photo from an old post.
lonniecook [at] aol [dot] com. I sold my '54 3104 12/12/2017, but I still visit Stovebolt.

OLD STUFF ... houses, furniture, cars, wine ... I love it all