Can anyone show me a diagram of the transmission line that flows out of the radiator after it’s been cooled by the radiator? I tried to locate a diagram I once saw on one of the sticky posts but am unable to find it now.

I have a 2014 SR5 premium with 140k on it. Change the ATF out yearly. Have dropped the pan and replaced strainer filter and cleaned magnets already. I’m trying to max out the life of the transmission. I’ve had amazing results running a magnefine atf filter on other vehicles less reliable than Toyotas. I owned a Honda Odyssey (2003 horrible transmission) and it made it to 390k on original transmission which the stealership couldn’t believe. I’d like to max out the life of my 2014 it has zero rust and plan on driving it till I’m six feet under. I’m pretty sure I know which line is outgoing but just want to be certain before I start installing the magnefine. Thanks for your help.

Just lay down under the front of your 4Runner and look on passenger side, you will see two steel lines running from transmission to the front, one connects to the hose running to the radiator cooler, the other is the return from the air-to-oil cooler in front of radiator. There is a odd shaped steel line beneath radiator that takes the oil from the radiator cooler and directs it to the air-to-oil cooler and then the hose that returns it.
Lay there for a few minutes and look at the lines, you'll figure it out, I'm in process of replacing all the steel lines on mine due to corrosion/leaks.

That line is marked with blue paint - you can see it next to the cooling system expansion reservoir, I made a post with picture regarding this when I was doing transmission fluid change, you can see it here: Transmission fluid (ATF) change (using the cooling line) 5th gen 4runner.

Thanks everyone who has responded this is very helpful.

Only V8 4Runner (4th generation like yours) have factory external transmission cooler, OP has V6 (5th generation), so it doesn't apply to his truck.

There are also some great pictures and diagrams in this thread.

Derale 13504 Transmission Cooler Install