Prototypes for this WalthersMainline Pullman-Standard 54' PS2CD 4427 Low-Side Covered Hoppers were some of the most widely used cars from the 1960s onward. Introduced in 1964 as shippers began transitioning from boxcars to clean-loading covered hoppers, these big and colorful cars could be found handling all types of grains, animal feed and many similar loads into the 2010s and in the 2020s some were still in captive non-interchange service.