Those are cool!
Eons ago, Stratton Mountain, a ski area in Southern Vermont, used those for their snowmobile needs. I don't remember seeing them anywhere else and back then there were a whole bunch of snowmobile manufacturers, such as Harley Davidson, Evinrude, Johnson, Mercury, Sno-Jet, Scorpion, Rupp, Moto-Ski, Skiroule, and a slew of others.
The Hus Ski machines were made by Bolens, and the follow-on model was the Diablo Rouge, not surprisingly painted red instead of yellow. Bolens is a name that's rarely seen today, but back then they were pretty well respected for their lawn tractors...