The book says the E4OD rear fitting is the return (back from cooler, into trans).

And the 4R70W Lower fitting (has one over the other) is the return for it.

Are these correct? The books sometimes have mistakes.

 

Generally the fitting that is closest to the bellhousing (converter) is converter out.

On ones that have the fittings stack'd atop of each other if you look closely you will see that one is closer to the bellhousing (converter) than the other.

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2000 F-150 Lariat, Flareside, Black, SC, FOxFO, 5.4L, 3.55, Garmin Street Pilot Color GPS

 

Assuming you're installing an aftermarket cooler- the bottom line from the radiator is the return line.

 

I just installed a cooler on my truck and it happend to be the lower line as the return one. I took off the top line and turned the truck over for about 2 seconds to find out if the fluid came from the line, or the radiator. It came from the line, hence, the lower line is the return line.

Hope this helps.