I want to add a new transmission cooler in-series after my stock cooler so that it can further cool the transmission fluid after it comes out of the stock cooler. Which line coming out of the stock transmission cooler in the radiator is the output? The top or the bottom? (referring to where the go into the radiator) Thanks in advance for the info!

Also, how do I keep air our of the system after i hook it up? or does it not matter?