I found the best spot to be the front of the intake and the head the second choice. On/off temps seem a bit low. Dakota Digital makes a nice fand control for single or dual fans(you can split functions for A/C or step control for low and high temp) It uses the temp sensor for you water temp gauge and you don't have to worry about where to place another temp sensor. But beware it is preprogrammed for popular gauges. It can be programmed for many applications but it is difficult.

http://www.dakotadigital.com/index.c...prod/prd43.htm