I have a pair 07 2500's. I started noticing the transmissions would get close to the max of what I felt confortable with.
We opened up the 'stack" or I mean We removed the radiator. What I first noticed is that the holes in the various devices as air passes through get smaller and smaller. The radiator is last, and has smallest, AC condnsor is largest.
So bugs and debris wil pass through condensor, intercooler, then in to the radiator, where they get stuck and block air flow.
Removing the radiator on both trucks, i noticed a lot of dead bugs, road grime, and debris. So using a lot degreasor and water hose, it took some effort to clean the raditor. I also u sed a power washer on low pressure making sure not to do a "sweeping action" in order to keep from messing up the fins.
Then spraying what was left in the truck, the intercooler and condensor from back to frount, this cleand the intercooler and condensor, and transmission cooler.
This made a HUGE difference in transmission and engine temps. I took a 7,000 camper all the way to Key West in July -August time frame.
I went from having to slow down to about 60 and lots of stops to allow wverything to cool off to having no issues at all.