At the end of World War II, railroads ordered large numbers of 50' AAR boxcars with a standard design that was first widely used in the late 1940s. This design was based on the original 1937 AAR design but was modified in the post-war era to include: improved dreadnaught end and diagonal panel roofs with standard or overhanging design. These 50' boxcars were a common sight on American railroads well into the 1970s and 1980s.
Details such as separately applied ladders and grab irons
Three different side sill styles - straight, tabbed and fishbelly