I found a radiator I'd like to use. It is a cross flow style, so the tanks are vertical on the left and right side. One of the ports is towards the bottom, the other towards the top. The pump that feeds the fluid lines within the trans - does it have enough pressure to push the fluid up say 18-20"?

More than enough. Much more. Get out your FSM and look at the lubrication pressure.

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Joshua

Cool. I know internal trans pressure is very high but I didn't know if that kind of pressure goes through the coolant lines too or not.

Lubrication pressure is supposed to be 5-15 psi with the throttle lever forward and 10-30 psi with it fully rearward according to my trans book.

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Joshua

From my experience with water cooling a pc pumps have a specified pressure and head height. Just using hypothetical numbers for example - 5 psi @ 2 ft, 10 psi @ 1 ft, etc until at a particular height it was zero regardless of what 0 height pressure was. This is what had me concerned. 5psi isn't all that much...

5 psi is the pressure at the return fitting. The pump will make a lot more pressure if you restrict the flow. It's a positive displacement pump, not a tiny little centrifugal pump.

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Joshua