Electric Fan Sensor Location

curious, what thoughts and rationale are here. I have a 283 in my ‘57 with an electric fan. The fan sensor is located on the outlet thermostat housing from the engine. Driving around I can tell it comes on while driving. My understanding is it should not provided the there is good flow through radiator.
1) placing sensor near outlet of radiator switches fan on only when outlet temp is high, and radiator not cooling well
2) sensor in thermostat housing clicks on when coolant at normal temp, dropping temp even further as it reenters engine.

Which is best place??
Paul

 

Mine is at the bottom of the radiator,works fine.

 

Mine is at the top radiator hookup. On about 210-215, off about 185-190. I'm ok with that.

 

Mine is screwed into the thermostat housing. On at 210 degrees and off at 195. I also have a 195 thermoset. I think my single wire switch came out of a Chevy Caviler.
My cooling system is really good. I can drive around all day with out the fans turning on. They only turn on when I'm on the trail driving slow or in heavy traffic.

The switch with GM connecter is on the left, the other is for my temp gauge.