[soutthpaw]

With shift programming, there is a big difference between gas and diesel mostly due to the fact that peak torque of 500+ ftlb stock occurs at 1600 RPM... also the torque stays closer to the max after peak than before it and as HP is a multiple of RPM, HP = TORQUE x RPM ÷ 5252 so if you can get the truck to cruise at or just past its peak torque then that should be most efficient. the 7.3's seem to have a sweet spot around 2000rpm. That's one reason I am thinking it would be beneficial to lock the TC early as possible on an empty truck that I rarely drive past 1/4 throttle 95% of the time. there is more than enough torque to move the truck effortlessly.