Along with Western Star, Hummer and Chevrolet it seems that also GM and Ford is coming to American Wilds edition according to swedish sales sites:
"This is Spintires: MudRunner – American Wilds Edition, the ultimate version of the indie hit Spintires: MudRunner.
Put yourself in the driver’s seat and take incredible all-terrain vehicles across extreme landscapes with incredible physics with only a map and compass as guides.
This Expansion comes with highly-requested additions, including 2 new sandbox maps inspired by the rough lands of Montana, North Dakota and Minnesota, new challenges to take on, and most importantly, nine of most iconic US trucks from household brands like GM and Ford.
In the Spintires: MudRunner – American Wilds Edition, drive 33 powerful all-terrain vehicles, and equip them with 60 add-ons to suit your mission! Complete your objectives and deliveries across 10 unique sandbox maps and 11 challenge maps set in the untamed landscapes of Siberia and Northern USA.
Overcome muddy terrain, raging rivers, and other obstacles that all realistically react to the weight and movement of your vehicle powered by the game's advanced physics engine. With your map, compass, winch, and your driving skills, go solo or join up to three others in the coop multiplayer. On PC, download mods created by the passionate community for truck-loads of content and an ever-evolving Spintires: MudRunner – American Wilds experience.
New to American Wilds
• 9 vehicles
• 2 sandbox maps
• 2 challenge maps"
And it seems that American Wilds Edition will be on Switch in november which means the Mudrunner Switch version will be released before or at the same time: