I am starting to put a transmission temperature gauge from B&M in my truck. Accourding to the instructions manual I should put the sender unit to the return line from the oil cooler. Probably cause that is the ATF which is going to be used in the tranny. But to me it seems more logical to put it in the line from the transmission (but I an not an expert), because that would tell me the heat of the transmission. I know they are the experts and are probably right but it doesn´t seem logical. Can somebody explain it to me? Jon H.