Not only do I know how to operate that old junk, I've Owned one of the conventional versions of those, the 57P and worked for an old dealer, but those days are gone now. I did have an opportunity to sit in the cab of an old model 86 cabover still operating as a fuel hauler out of Texarkana Texas. Driver was the original owner. Met him at a truckstop in East Texas, as I was a Marmon fan, and had not the opportunity to entertain any of their cabovers, a class of truck of which I was intimately familiar.
