Normally there was one thermal switch in the lower radiator connection that was calibrated to run the electric fan. The best location for an after market water temperature probe is in one of the threaded ports in the top front of the cylinder head. With some probes you will need to make a spacer adapter from pipe fittings to increase the depth of the cylinder head port. The other opening in the lower radiator connection was used for the return line from the heater core to the suction side of the engine's water pump.More questions!
My stock outlet has 2 water temperature probes. Are these used? Why measure temperature on the inlet to the motor? I would think you want to measure the temp at the outlet of the motor, or in the head.
I see some inlets have water ports. What are these used for?
My real question is do I need to install threaded inserts in the tube for anything. I left enough room that I can put in at least 1. I will have to check for clearance before welding them in. Has to clear the ac, alternator, motor mount, and who knows what else.