In 1949, the Budd Company began developing a lightweight, self-propelled diesel rail car for local and branchline passenger service at the request of the New York, Susquehanna and Western Railroad, and the resulting Rail Diesel Car, or RDC, quickly gained nationwide popularity as railroads sought lower-cost alternatives to abandoning money-losing passenger trains. Efficient, easy to maintain, and requiring only a two-person crew, RDCs were also offered with baggage or mail sections, and 368 were sold to twenty-five North American railroads, including the Lehigh Valley. Built by the Budd Company at Red Lion, Pennsylvania, in August 1951, Lehigh Valley No. 40 was one of a pair of RDCs, Nos. 40 and 41, ordered for service between Hazelton and Lehighton, where passengers could connect with the railroad's intercity trains; No. 41 was equipped as a combination coach and baggage car. After the Lehigh Valley ended all intercity passenger service on February 4, 1961, No. 40 made the last run from Hazelton four days later, marking the end of scheduled passenger service on the railroad. Sold to the Reading Company and renumbered 9163, it then operated on commuter trains out of Philadelphia until the Reading's 1971 bankruptcy, after which the Southeastern Pennsylvania Transportation Authority continued using it until 1984. Donated by PennDOT to the Railroad Museum of Pennsylvania, the car arrived in Strasburg under its own power as the first RDC preserved at an American railroad museum.