In the mid-1970s, Santa Fe rebuilt three Alco RSD15s with EMD components and dubbed them CRSD20 diesels. These were used on the hump at the railroad's massive new yard in Barstow, California, which was completed in February 1976. These engines were mothers to drones (slugs), built from old Alco RSD5s and RSD15s. Seen at Barstow on August 25th, 1976, are Santa Fe CRSD20 3900 (ex-RSD15 9828, nee-828) and CRSD20 3901 (ex-RSD15 9826, nee-826).
