It is a 1960 aluminum-cab Peterbilt that came stock with a 12 cylinder Detroit Diesel sporting twin 6-71 blowers.
At Thursday night's Baja Cantina event, he hooked up with the Mother's Wax folks, who had him drive to Saturday's Laguna Seca event for display at their tent. Randy fired up the beast every hour or so, and you could hear it throughout the track area.
It is for sale at an upcoming auction if any of you want something a bit different.

Larry
Yup, yours truly sitting behind the wheel.