Operating Era: 1910-1958. Atchison, Topeka & Santa Fe. THIS SERIES NOW COMES WITH OUR ONE-PIECE ROOF FRAME. These Santa Fe cars represent a steady progression of car building based on the standard 36` DS truss rod box car. The Bx.W was the first to have steel underframe members to strengthen the wood floor. The lower third of the end was also steel. 5,000 were installed in 1910. Within a few years safety appliances were added. 3,250 Bx.X class cars were received in 1912-13. The cars came with safety appliances and slightly different lettering. In 1914 500 Bx.Y`s arrived with strengthened doors. Finally, 1915 saw the Bx.Z cars with wraparound steel ends (see kit 1401). Bx.X and Y cars were converted to Bx-15/16/17 in the 1930`s by swapping trucks with other classes. All 7 classes lasted into the late 1950`s. Our lettering and details allow each class to be modeled throughout its life. Each kit is physically different.