I added a Tru-Cool Transmission cooler when I had the Tranny beefed up.
Normal temps 140F~160F and up to 200F towing 30ft 5th wheel in summer on hills.
I added it in series , retaining the stock one.... easy to do...Happy with results!
Islander
2000 F350 7.3 Dually 90k miles , 4" exhaust turbo...