Electric fan thermostat install

[edhd58]

I have a question about where to install the electric fan temperature sensor. Should I install it on the thermostat housing monitoring the temperature of the water going to the radiator. Or on the water pump housing monitoring the temperature coming out of the radiator?

There are two outlets on the water pump I can hook the sensor into. The one on the front will have a constant flow of water across it, the one on the side I have to put a tee on there to run my temperature gauge and the fan temperature sensor. The one on the side will not have a constant flow of water across it it's a blocked line. If I put it on the thermostat housing I feel like I need to put it on the front hole where I have to put an adapter but it will have a constant flow of water across it to get a constant correct water temperature.
Am I thinking correctly that it needs to go on the thermostat housing on the front what will get a constant flow of water across it?