2004 4l80e hot trans on hills

My 4l80e ran ‘hot’ when I was towing my toyhauler (10K loaded) and I didn’t feel comfortable with the tranny at 190 – 230 degrees. So I installed a Tru-Cool 40K. I now tow at 155 degrees in 100 degree weather with the highest temp being 185 pulling grades.


I think its obvious why the stock cooler doesn't work so well:




Here is the installed I copied when installing the cooler on my 2500hd:

http://www.gmfullsize.com/forum/showthread.php?t=253688