(an old mechanics trick) Start with a cold engine and transmission. Start car and feel the tranmission lines going into the cooler. the input line will begin to heat up as the transmission heats up. the cooler of the two lines (to touch) will be the return line.
Got it and thanks for letting me know. How about the radiator with trans cooler? the trans connects to the radiator but i can't remember which is the inlet and the outlet..
I can't seem to find any diagrams for the radiator. the only detail i found was "Trans cooler hoses" pointing towards the 2 hoses at the bottom of the radiator but i'm not sure where to connect those to the trans.