Re: ??? Fan Clutch ???
I agree with Riolobo's post 100%. The way these things work is that as they heat up they allow the fan clutch to slip a little, thus less fan rpm (noise reduction) and a little (less than .5 hp would be my guess). I also don't run the clutch fans in my rigs. Most off roading is slow going you need all the cooling you can get to keep that 700 pounds of steel cool.
If your not living on the edge, you're taking up too much space.