http://www.tod.com/productdetail.asp?ProductID=89
good thermal switch resource for those considering an electric fan.
this would screw into the engine or radiator ,,or elsewhere as you would find results to be best reguarding when the fan kicks on as it relates to temperature.
parts required
your choice electric fan
high wattage/amperage automobile relay from a junk yard, or no relay, just a pos wire to fan
wiring
thermal switch installed on the ground side of the fan.