With ALL DLC included, you have immediate access to every truck brand available in that era:

When seeking the "Incl ALL DLC" version of 1.6.1.8s, players are looking back at a time when the game's core features were being refined with "driver experience" at the forefront. Key Features of Update 1.6

American Truck Simulator v1.6.1.8s: The Definitive Legacy Experience