The first of these two, number 4000, entered service on May 26, 1909. It was rebuilt as a cab forward and reclassified as an MC-2 in June 1923. Another rebuild on June 4, 1931, "simpled" it with uniform cylinders and reclassified it as an AC-1. 4000 was scrapped on April 2, 1948. The second locomotive in this class, 4001, entered service on May 30, 1909. It was rebuilt as an MC-2 in April 1923, "simpled" on February 9, 1931, retired from active service on May 23, 1947, and scrapped on June 14, 1947, at SP's Sacramento shops.