red58,
The history of the truck indicates that it was originally purchased and used by the California Forestry service, and the rumor would be that they put in the fan. A fan would seem to be a good accessory in such a truck. The rumor came from the previous owner, who was selling off parts and vehicles for someone else. He seemed to recall the fan when I asked him about the connector, but had sold it previously with a box of parts. So, the rumor is not very strong...
