The Silverliner coaches were first built by Budd in Philadelphia and used by the PRR in 1958 as the Pioneer III for a prototype intercity EMU alternative to the GG1-hauled trains. Similarly designed cars were purchased in 1963 as Silverliner II units. In 1967, the PRR took delivery of the St. Louis-built Silverliner III cars, which featured left-hand side controls (railroad cars traditionally have right-hand side controls) and flush toilets (since removed), and were used primarily for Harrisburg-Philadelphia service. The Silverliner II and III cars were designated under the PRR MP85 class. Some Silverliner III cars were converted for exclusive Airport Line use; they featured special luggage racks where the old toilet closets were located, yellow window bands, and the Philadelphia International Airport's PHL" logo. The bulk of the fleet are Silverliner IV coaches built by General Electric in Erie with carshells from Avco and Canadian Vickers; these were delivered in 1973–76, before the formation of Conrail.