Among the first standard boxcar designs adopted by American railroads, the WalthersMainline 1937 40' AAR Modified Boxcar features:

1000s used in general service late 1930s to 1980s
• Based on taller cars built with 10' 6" interior height featuring:
  • 5-5 Dreadnaught ends
  • Murphy panel roof
  • Wood running board
  • 6' Youngstown doors
  • AAR (tab) side sills
  • Correct 33" RP-25 turned-metal wheelsets
  • Proto MAX(TM) metal knuckle couplers