Auxiliary Transmission Cooler
Heat is the enemy of transmission fluid, therefore the enemy of the transmission. Kept below 175f you can expect the fluid to last 100,000miles, at 195f expect 50,000miles, at 240f only 5-10,000miles, so yes, heat really matters. This depends on the transmission oil that you are using as well, some perform better than others. But keep it cool and it will last longer.
Here is the transmission cooler that I installed in front of my radiator to ensure that my transmission temperatures remained as low as possible while loaded/towing. http://amzn.to/2pQbzyp
I also ordered the 5/8-18 inverted flare fittings so the factory lines were not modified and could always be returned to stock if needed. http://amzn.to/2qNlEJM
Installation manual: http://www.haydenauto.com/Upload/HaydenAuto/documents/InstructionSheets/P-468-transmission-oil-coolers.pdf
Here is how the transmission cooler lines are from the factory:
Here is the recommended installation for an auxiliary cooler:
Orientation of the transmission cooler matters as well, if the fittings are pointing down it can create an air pocket(s) in the cooler:
