Unit 344 was built in April of 1953 for ATSF as part of order #6501-A. It was later rebuilt for ATSF to CF7 2525. The Santa Fe was noted for long strecthes of running where speeds over 100 mph was authorized, and it retained an extensive fleet of passenger trains until the late 1960s. As a result, the passenger F7s remained in their intended service longer than equivalent locomotives on many other railroads.