Jack, I have that type trans pan and it sure can't hurt cooling because it adds more fluid volume as well as having tubes but it does reduce ground clearance. I just received my Speedway Catalog #356 and on page 213 there is a Derale "Remote Fluid Cooler" for about $180. It appears to be 5" thick and might fit under your rear pan. Unfortunatley I mounted my battery in the rear between the exhaust pipes and could not find a place for that type cooler and so I ended up with the angle mount of a passive cooler under the right front fender.

Don Shillady
Retired Scientist/teen rooder