If you don't have a tranny temp gauge now make sure and buy and install a good one so you don't run the tranny to cool, ATF needs to be at least 160F to work properly, not below that
Domnic, Thumper Dart, found that out when he installed one that looks like the one in your post in front of his radiator mounted flush to it, he ended up mountiing it sideways behind his front bumper to get it to run 160F+ in the summer in the Mojave Desert in the middle of the day
Most stock tranny coolers in the bottom of the radiators are tranny heaters, not coolers