Are you looking at the small cooler on top of the radiator/air conditioning condenser?
Are you aware that there is the heat exchanger between engine coolant and transmission fluid on the passenger side of the block under the turbo? That's where fluid goes first on a stock installation, then to the little cooler up front. The need for the heat exchanger is to get the trans fluid up to operating temp if it's really cold, or to take heat from the trans fluid if that is really hot.
When Dodge supplied as an option their "Superduty" cooler, they mounted it under the driver-side truck bed ahead of the wheel. It had a fan to move air thru the cooler and a thermal switch that controlled when the fan turned on. This cooler by the factory installation instructions got cut in ahead of the heat exchanger, effectively at the output of the trans - fluid ran from the front trans line to the Superduty, then to the heat exchanger, then to the cooler up front, then back to the rear connection on the trans. I have no idea why they did it this way, but they did. If you want to see the "Superduty" instructions, give me an e-mail address to send them to - it's a large file.
Lots of folks have put a similar fan-and-cooler in the same location, with some putting it in as Dodge did and others putting it last - just before the return into the trans. I guess it's a matter of preference and viewpoint on how it ought to work.
Some pictures of the Superduty and lines to it are in my pictures.
Regards, DBF