Trans cooler question

[86TType]

I have purchased a transcooler from a local parts store and i was gonna run it in a series through the rad. But which line do i leave hooked up to the rad and which do i run to the cooler from the transmission or it dont matter which i use? Any suggestions? Thanks

 

[Sinister CO]

I left the bottom line on the radiator and ran the top through the external and back to the transmission. I believe the bottom line is the output from the transmission. I wanted to run it through the radiator first and then through the external, thinking that would give me the best cooling.