Trans line ideas

I have seen these transmission coolers put between the bed and a cab of a truck with no fan at all and did fine working in the hot fields in Florida at low speeds and run all day, and drive 40 miles to plant City Florida loaded down with about 200 flats of strawberries and did it well over 5 years with out anyproblem, there must be some cool air there or something Pete.
How cool do we need to keep our transmission fluid ?? :scratch:Makes me wonder :-k, we know it hits 180 degree or higher radiator to get cooled, does any tech have info on this ?