Wow, I just realized I never said the horsepower or torque in the video, didn't put it on screen during editing, and forgot to comment it before now. 146 HP, 270 lb-ft according to the engine manual. If you're really nerdy, those are the gross horsepower measurements at the crank. The service-ready measurements are 127 HP and 230 lb-ft. This is because of all the accessories and the more restrictive exhaust manifold. Also keep in mind that these numbers use 80 octane gas.
Yeah, I should have remembered to look over there. I think I was confusing it with the GMC M-211 that I also have, on that truck, the data plates say the top speed is 55, but an early version of the manual said 58. The army figured that driving at top speed wears things out faster, so they lie to the lead-footed teenagers they enlist so the trucks don't wear out. Of course, you'll also find people who will swear they've driven these vehicles at 70 MPH for four hours without any problem. I never plan to drive it above 50.