For 5.9 engines, do not add ATF to your fuel. While older ATF fluids were just light hydraulic oils, modern ATF+4 is full of friction modifiers that can cause injector pump and injector problems. Also, ATF has a flash point that is much too high to ensure a complete burn which can cause to injector clogging and poor spray pattern.
If you wanted to run something for ultimate lubricity, a good diesel fuel additive or even a 2 stroke oil (engineered to burn clean) would be something to consider.
That all said, for a 6.7 truck with a DPF, I would not run anything but straight ULSD and perhaps a diesel fuel additive that is compatble with ULSD. Running ATF, 2 stroke, or other additives that are only compatible with LSD fuels can cause major issues with your DPF. The 6.7 is made to run on ULSD. Adding other additives will clog the DPF and regen won't remedy the situation over time.
-Chuck