Trans cooler

your transmission should run 180 - 190.
I used an external cooler alone with a warm 340 and a 9 1/2" Dynamic converter and never saw the temp over 160...not good.
I would run it through the rad to help keep it warm.
I doubt if they would make separate rads for the southern states..and if they did at what north south mile would be the
changeover?
..i suppose running your trans fluid through a 180 radiator could regulate it somewhat..it's only an 8" double wall tube.