Budd revived its railcar concept after diesel engines with a suitable combination of power and weight became available in 1938, although with more conventional steel wheels. In 1941 Budd built the "Prospector" for the Denver and Rio Grande Western Railroad. This was a two-car diesel multiple unit. Each car had a pair of diesel engines and was capable of independent operation. The cars were constructed of stainless steel and included a mix of coach and sleeping accommodations. The design was popular with the public but undone by the difficult operating conditions on the D&RGW. It was withdrawn in July 1942, apparently another failure. However, several technical advances during the Second World War encouraged Budd to try again.