Originally built as Union Pacific 800-class steam tenders in 1937, UPP 809 and UPP 814 have both undergone significant changes over the years. They were used as fuel tenders for the GTEL 8500 Horsepower “Big Blow” Turbines in the 1960s, fuel storage tanks in the 1970s and finally entered water service for the Heritage steam fleet in 1989.