I remembered a trip I took once when we were firewood logging. We were chased out of the woods by the winter snows, and had resorted to buying log loads to keep busy.
An owner operator from my small town had a 1965 351 "needlenose" Peterbilt, and I went along with him to Peoh point above Cle Elum to get a load. We chained up to get up the hill, got loaded out and headed for Selah.
He was a man of few words, but I got from him that it was an 8v92T that had been "turned up". He had twin sticks, 5 and 4.
I know the firewood loads are light and cured out, but that thing was still fast.
We rolled onto the Manastash Ridge hill out of Ellensburg. He dropped one gear, moved into the left lane, and passed a long string of trucks crawling up the hill. i think back on that ride and realize he had put some time and money in building that truck.