The D8 Dozer is a bulldozer manufactured by Caterpillar.
One of these is used at the Big Nugget Mine, another was used in season 2 at the Quartz Creek Claim.
A 50-year old D8 was borrowed by the Dakota Boys to clear snow off the road in season 4. The dozer had not been run in 5 years, and instead of hydraulics, used cables to control the blade.