the best place for a temp sensor is to put it in the pan. thats opperating tempeture. the front cooler line is the hottest oil coming from the convertor, not accurate. the pressure port shown in the picture is for rear band apply, also not accurate.
Considering the case is made of aluminum which is a fantastic heat sink to distribute the heat fairly evenly throughout the trans I can't see how the temp at the rear band apply port would be much different than the pan temp. And consider this, the pan is hanging down in an area of air movement so it'd be naturally cooled and not provide any more accurate reading than the oil at the band apply port.
