my next big upgrade to the transmission will be dropping the temp threshold window for the engine cooling fans. This is another factor in maintaining heat resistance. even as i run a 175 stat, stop and go traffic causes the engine to get up to 205 F , its not til i'm on the highway that i can cool the transmission by utilizing the radiator heat exchanger. i'll let you know my discoveries. this weekend i drove 80 miles at 70 mph, nonstop it held a constant 125 F all the way out of town. with NO aux trans cooler! just 1/8" restrictor in the bypass system
funny thing is my 2012 Sierra 2500HD with factory tow package also operates at 120-125F and that truck has a monster trans cooler from the factory