Atlas Trainman HO 20006239 1937 AAR Box Car Kit, Lackawanna #51500Atlas Trainman HO 20006239 1937 AAR Box Car Kit, Lackawanna #51500 Part Number: 843069180319 Description Atlas Trainman HO 20006239 1937 AAR Box Car Kit, Lackawanna #51500 The 1937 AAR Box Car is widely recognized as the first standard freight car design to be voluntarily adopted by the majority of railroads throughout the United States. Although previous USRA designs also achieved widespread distribution, their success was mostly due to government