Hi guys, was wondering if anyone knew how to identify which line going to the stock trans cooler was hot and which line was cooled. In the middle of adding radiator in the trans cooling loop.

Run engine for 10mins or so,the hotter line is the feed line(from trans) and the cooler one is the return line.

Thanks tjkj. I tryed that but found both were about same temp and couldnt really feel a temp difference. The wife thought gettng new pumpkin pie ice cream was a good idea and of course, it was a brilliant idea. So about a10 min drive to dq and checked tubes then. Upper tube I could put my finger on no prob, hot but not burning. Lower tube I couldnt rest my finger on for more than a second before immenent burn alarms sounding in my head.
So the lower (entering enginebay from trans) that goes to the FAR side(drivers side) of the trans cooler was hot.
Heads up to anyone else doing this- connect hot line into top radiator input. Then run hose from bottom output of radiator to cooler. Also be warned the quick connect fitting that originally connects trans line to cooler is an ultimate bear to remove without whatever disconnect tools that are available. Ended up cutting the end of quick disconnect carefully into 4 pieces and gently bending them back off the cooler input.
Go to the junkyard and pirate a dodge durango for radiator input and output. Also cut yourself a good size piece of that hd rubber tubing you see everywhere (a little more than two feet) to connect from lower radiator to cooler input. Got a tubing flair kit from harbor frieght for line to and from radiaror which of course broke but was still able to flair tube ends (then returned to store). And some small hose clamps from home depot to clamp hose ends. Its alive! and no leaks!
Didnt take pictures but will of finished project soon