Accessory by Ford, there were a lot of nos kits for sale by one of the parts dealers back on in the last century—-car, pickup—- I don’t know about big truck, it should be in the “green book”
They are literally everywhere. It was an accessory. The hard part to find is the temperature sending unit for one the sending unit is 20x harder to find than the fan itself. They at full speed rotate slower than the factory belt driven unit. Personally they are a neat piece but not worth much as they are unrepairable