why would it need to be on the top and return on the bottom?

I thought you would fill it from bottom to top of cooler when horz

thats the way I took the stock one I pulled from an 87 dippy police car off

I put it back the same way on my truck,seems to work fine so far

wouldnt the tranny pump and cooler stay some what full with it feeding from bottom to top and not leak down?

man I dont want to change them back around,I just got it done