Originally Posted by performabuilt

My point was the trans will cease making heat when not running. While it will in fact make heat running even in neutral or park, This I have observed on the dyno. With little air flow just setting there spinning yu can in a relativley short period of time reach temps of 160 as I have noted. Now it would be true if you have been running for instance at the track and were above engine temp with the trans idling would get you down to that just running at idle park , And running with just a cooler and no pass through the radiator you would cool down even more if you have good air flow. But perhaps I miss understood I thought what was ask was after driving the truck and when done ready to park should you let it set a idle a bit before turning off to cool down and My answer to that is no,
Of course IMO if you not getting over 230 degrees to start with I wouldn't worry about either and if you are you need more cooler anyway.