Spurred by the postwar business boom and in an effort to replace worn out equipment, North American railroads built large numbers of 40′ boxcars to the AAR standard designs beginning in 1945. Prototypes were built with different combinations of roof styles, ends and doors. Models feature highly detailed tooling, many separately applied details, 4 different end styles, 2 different roofs, Superior or Youngstown doors, 7 or 8 rung ladders, fully detailed underframes, free-rolling trucks with blackened metal wheelsets and prototypical paint schemes.