Steve, where I am now, the county road dept used to use 6 cyl GMC powered Clark (like Austen Western) road graders for snow plows. Until recently, they still had one in use to plow one route 10 miles north of where I am. As you say, on a cold winter day, I could hear it running 10 miles distant.
There is a thread on this site about FMC skidders built on M-113 armored personal carrier drivetrains. There is a vid on that thread, of a FMC skidder working in a swamp. The sound of the V-6 two stroke is evocative; five minutes of memories came back when I heard it. Near by to me, there is a machine that I can't stop thinking about buying, not that I can use it, that is powered by a 12V-71.