I have the two speed volvo fan I got off ebay, now I just need to get a thermostat controller. I plan to put two switches in the cab, one will be a 3 position switch for manual on, manual off, and thermostat on, the other switch for hi-low speeds which will work with both the manual on and thermostat on positions. The only issue with that is remembering to not leave the first switch in the off position ever, except for water crossings. I also plan to use either a lighted switch or a separate light that shows when the fan is running. Lots of wiring and places for failure. Will try to have a nice wiring diagram written up since its hard to find a good one that shows a setup for a two speed fan.