The Wabash first built 40' box cars with 8 ft doors in 1951. They were numbered 6000-6299. The next year the railroad built the last 40' cars with 6 ft doors numbered 7000-7299. All new 40 ft box cars built or purchased after 1952 had 8 ft doors with the exception of the 91000-91514 series which were built in 1961 with 9 ft doors.
