4004 began life as a post war design President's Conference Commission ("PCC") car built as Pittsburgh Railways 1739, a city car. It was built by the Saint Louis Car Company (Order number 1669) between November 1948 and May 1949. This car originally rode on two B3 trucks each mounting two Westinghouse 1423K traction motors with a Westinghouse XD423R controller. This car was built to the Pennsylvania Trolley gauge. This car was acquired by the Port of Allegheny Transit (PATransit) as of 1st March 1964, retaining the number 1739. This car was rebuilt during 1988 receiving a pair of Creusot-Loire B3 trucks, retaining the earlier electrical equipment and was renumbered to 4004. The modernised 4004 was retired circa 1999 and was acquired by the Pennsylvania Trolley Museum during 2004.