The BNSF Officially Licensed ES44AC & SD40-2 RailWorks Add-on is now available for purchase on Steam to customers who purchased the retail version of the base game. The BNSF DLC is already included with the Steam version of RailWorks.
Source The BNSF Officially Licensed ES44AC & SD40-2 RailWorks Add-on is now available for purchase on Steam to customers who purchased the retail version of the base game. The BNSF DLC is already included with the Steam version of RailWorks.
Source