Automatic transmissions need good size coolers in front of the radiator. My book on my chevy says change the fluid every 100,000 miles. I'm gonna change it next week at 22k miles. I went and bought a transmission pan and had a drain plug fitting welded in. 2 months ago the body control module died. It was cold and the battery got low, low battery killed it. Installed a Optima advanced glass matte battery. These newer technology trucks suck. So finicky! I keep an eye on the truck forums, as these guys are very good at fixing the vehicles and doing preventative modifications. Some of the shittiest engineering I have ever seen...