This is a picture of a 12K original mile Fire Truck interior showing the correct locations for the knob/cable and the switch if you look here under the dash you will see the pre-drilled holes. I have seen that fan switch in some trucks but believe it to be after market. The heater is the correct one for your truck havng the small door. Here is a picture of the switch, they come in different colors some light others darker. Send me a PM on the clip. Last picture is of my early style recirculating with plate instead of decal correct for 47-50 trucks. Plates/decals are changeable for GMC or Chevrolet.
http://good-times.webshots.com/photo/2282825960102454676njXUMqhttp://good-times.webshots.com/photo/2400227690102454676PcEfGNhttp://community.webshots.com/photo/2721657400102454676GytrQtDakota,
Heater 1 is a decal type recirculating correct for 51-55 1st series trucks.
Heater 2 is and Air-flow correct for 47-50 with plate instead of decal.
Heater 3 is the same as 2 but missing a plate.
Heater 4 After market (lots of different kinds).
Heater 5 41-early 47 vintage heater.
Heater 6 like Heater 2
Heater 7 is a decal type Air-Flow 54/55 1st series heater they all have the little interior door.
Heater 8 After market
