On my 41' Willys (Chevy 350 mild build) the electric fan stays on to long. I had to replace the sending unit last summer (On vacation) when the fan stopped working. The parts man sold me another sensor that bolted to my intake manifold and the fan worked fine except that it stays on to long. I don't know the part number of either the old or new sending unit, anyone know a good part # sender to use so that my fan doesn't stay on to long... It usually runs for 5 minutes after a ride on the Hi-way (I run a 180 thermostat).