The PRR CLASS X-31 box cars had a novel roof design named the "round roof" or "wagon top". By curving the roof sheets to meet the eave bar vertically (leaving a 4" inset on the edge) the cars had an inside height of 10'. The X-31's were used primarily to transport new automoblies or auto parts. The majority of X-31's are in the X-31, X-31A, X-31B and X-31C sub classes. These classes had very minor external differences. The X-31's were first built in January 1933. In 1935, the roof of the X-31's was redesigned, with a new inside height of 10' 5" in the center and 10' 0" at the sides. The external appearance changed with the roof sheets overlapping the side sheets at the eaves. This gave a flush apperance to the roof as compared to the inset of the original design. By 1936, the single door X-31A had replaced the X-29 as the general service box car. The X-31's were used on the Pennsy throughout the 1940's, 1950's, and the mid 1960's. The following X-31's were in service: 8,574 cars in 1936; 10,496 cars in 1939; 9,786 cars in 1944; 9,702 cars in 1953; 9,522 cars in 1960; 1,038 cars in 1968. The Seaboard purchased 1200 double doorcars and 500 single door cars in the 1940's, the Detroit Toledo and Ironton purchased 400 double door cars in 1937 and the Norfolk and Western purchased 300 cars double door cars and 1300 single door cars between 1936 & 1939. In the late 1940's the DT & I sold all its 40' round roof cars to the Northern Pacific. Later the cars were sold to Manufacturers Railway and Detroit and Mackinac.

KIT INCLUDES: injection molded plastic body, doors, roof walk, brake wheel, X2f couplers, one piece molded (coil semi-elliptic spring) trucks and 33" chilled wheels with RP-25 flanges on brass axles. MADE IN USA. Our model is a prototype Pennsylvania X-31A class box car kit with INSET & FLUSH ROOF. The production molds were made using the original PRR drawings as our guide.