does it matter which way ?

You guys are confusing expansion of water and psi for that of oil and psi...

the trans does not use a cooler the same way a radiator is being used....

It is a continuous flow and gets cooled as much as possible before returning to the trans...

This is why being stuck in the sand/mud/snow KILLS transmissions, there is no real cooling for it, it is a best you can get run thru design there is no real way to regulate and cool a trans without a very involved liquid to liquid exchanger

You can put it top, bottom, sideways, backwards, whateverwards. . . .