What trans in a 2005 Ford E450? Trans cooler recommended?

I installed the TruCool on my E4OD without the thermostat too. I live in the South with few really cold days. I always figured I'd use a piece of cardboard or plastic on the grill if I operate the RV in freezing temps, which I avoid doing anyway. The larger cooler really helps. I was seeing temps 220F and over sometimes. No more.