Operating Era: 1923-1973. THIS SERIES NOW COMES WITH OUR ONE-PIECE ROOF FRAME. Atchison, Topeka & Santa Fe. A double sheathed box car with partly visible steel frame, the Bx-3 is unique in car building. Santa Fe received 4,000 cars from AC&F, Pullman and Standard Steel in 1924 and another 1,000 visually identical Bx-6 cars from Pullman in 1925. All were delivered with plate steel doors which were soon strengthened with braces. By the 1930`s corrugated doors were replacing the plate doors but the latter could be seen for many years. In the 1940`s AB brakes were applied. Cars ran into the 1960`s. Some cars were rebuilt to carry stock and some were insulated for ice and salt. See our kit series 3700 for reefer versions. PLEASE SEE OUR DS BOX CAR AND OUR REFRIGERATOR SECTION FOR OTHER #3600/#3700 SERIES KITS.