Allan I think you tune or play with tuning on class 8 trucks.. when was the last time you adjusted horsepower curve in a file? Also your truck probably has 480hp at lets say 1900 +- rpm and peak torque at about 1500rpm when you hit a big hill or a long steep grade notice where the tach settles in ? I bet around 1500 where peak torque is... you may get a run at the hill with the horsepower but when it settles in its the torque doing the work.
Yes 1500 is where peak torque is. Yet if I can't pull a hill at say 60 mph at 1500, I split a gear to 1700 and suddenly I'm pulling it at 60 mph? Engine torque is lower, HP is higher, and I'm making more torque to the wheels.
Also the torque wrench analogy makes me LOL. How much torque can you make on one personally? So what if you were in the engine bay of a car with your torque wrench, would the car go anywhere? It would barely move. You can make a decent amount of torque but it's at such a low RPM it is quite useless for doing any actual work. The human body can produce a lot of torque, but maybe 1/5 a HP.