Alyeska Had several of these. they use a pair of hydrolic motors and 2 additional ring gears in the rear end to steer. If you break one of these it's about 30,000$ to fix, or at least that's what Bombardier charged the Pipeline. They( Alyeska or the "Trans Alaska Pipeline") had 44 Tucker Snow cats and purchased 5 or 6 of these. But the Tuckers would out perform the Bombardier's and the guy's didn't like taking a chance that the thing might break down out on the Tundra at 40 below. Eventually they sold off the Newer, 1987, Ski Dozers. Alyeska's machines had: 2 sets of tracks, a removable 'Man Box' that would hold about 10 people, removable dump bodies, a front blade, and 2 of the machines also sported a crane or back hoe attachment. They cost a whopping 485,000$ with all the attachments. I went to inspect some electrical work on the Pipeline near Valdez and Thompson Pass in one. When we completed the work we loaded a generator, a pipe threader, lots of tools and a couple ladders in the man box along with 4 electricians. The rear double doors kept poping open so we wired them shut from the outside. The Operator and I were in the cab wearing hearing protection when we started hearing this thumping sound going up this long hill. Seems a fairly large fire extinguisher had fallen over in the man box and discharged. Fortunately there was a pop top roof hatch and the guys all had there heads out gasping for air. One of those experiences you don't readily forget! Theirs had the Dodge Turbo cummings Diesel. Good luck with your new machine.