Okay, so how would one wire in thermos in an F truck with a 351C?

Same way you'd wire them in any other car.
You'll need a thermatic switch of some sort as a trigger.
Craig Davies etc.
Use that to trigger the relay that will turn on the thermo/s

So how/where do I add the sensor/switch?

Thermostat housing is always a good place.
Or the same place as the sensor for the coolant gauge, where ever that may be.
Where there is coolant flow basically.
Some of the switches might have a screw in sensors, others just have a probe that you stick in the upper rad hose and clamp over.

No offense but it's all pretty self explanatory, if you look over any EA-ED thermofan conversion thread it will cover the same basic stuff.

Fair enough, I wasnt sure if it was easy on the EA-Ds because of the EF/Ls factory fitted or what.
If its pretty universal then it should be fairly easy. Thanks Steady