The Kenworth Truck Company was founded in 1923 and are celebrating 100 years as a truck manufacturer! And since their trucks have been in American Truck Simulator ever since the game was released it is understandable that SCS Software is joining in the celebrations.
In particular this is done by releasing a new, special anniversary edition of the classic looking Kenworth W900 in the game, based on the real-life special edition from Kenworth.
This in turn also means that SCS took the time to go back and remodel the old standard versions of the W900 as well so that their visuals would be brought up to today’s standard in the game. They were after all in the game from release, so they did have a couple of years under their belts by now.