Peterbilt 389 Deck Plates & Air Line Boxes Upgrade your Peterbilt 389 with high-quality deck plates, air line boxes, and accessories. Choose from stainless steel, aluminum, or diamond plate deck plates and a variety of air line boxes with convenient hookups for trailer air and electrical. This product line includes helpful accessories like filler sections and billet aluminum step plates, allowing you to create a seamless, durable look for your truck's undercarriage. Perfect for upgrading or equipping a new truck.