As the need arose in the 1930s for greater car capacity, many railroads found themselves constrained by tunnels and other tight clearances. One solution came from the Pennsylvania in 1933 in the new X31 class. The X31 and similar X31A subclass were easily identified by their rounded roofs. In a few years, the AAR adopted a slightly different variation of this initial design which was picked up by multiple railroads. The Seaboard continued to reorder cars based on this basic design into the 1940s. Finished automobiles were a common load for the double-doored variation of this design but the large door openings quickly found favor for lumber loading as well as machinery or other large loads. Some cars would be rebuilt in later years and many survived into the 1960s. Our first run of the double-door X-31's in over a decade, these cars are perfect for service on any layout!