[45jim]

Diff coolers are very common on race cars, you'll find plenty of sites where they warn of diff oil exceeding 280F during use. On diffs exposed to the airflow a finned aluminum cover is usually enough to deal with excess heat build up. With Independent rear ends where the diff is tucked up out of the airflow a small cooler with pump and fan are often placed in a remote location in the airflow for races. With this diff being all buttoned up and totally isolated from the airflow the addition of a cooler would be a common requirement. I am sure the diff with the windows was to determine where to locate the pickup tube. When you install one its important that the pump not suck air as that will aerate the fluid further degrading its lubricating qualities. The normal method is to use a plastic diff cover while the vehicle is run on a dynometer and see where the fluid is, and isn't.