Help Please. which tranny line is the return?

[Limbwalker]

Ive read a ton of threads with guys bypassing the Radiator and installing their tranny coolers, But cant find a write up for doing it in series with a new radiator....
This is what I am doing, and My question is, How do I tell the 2 lines apart? Thanks

 

[Limbwalker]

Sweet...NM, Found this on yotatech

 

[KidVermicious]

Unplug one, turn the truck on. If the one you unplugged squirts oil all over your driveway, it's the send line.

 

[19963.4lsr5]

Sweet...NM, Found this on yotatech

There is another picture somewhere that shows the lines at the front of the engine.

 

[19963.4lsr5]

Here it is at the rad.

 

[Doc2012]

Why run it in series?

That's not going to save you from the milkshake.