Group: ATSF 7513-7519 Railroad class: 7500 Builder number: GE 37111 Builder date: July, 1969 Prime mover: Turbocharged GE V-12 FLD12 Main alternator: General Electric GT598 Traction motors: Six General Electric GE752 Production: 223 units between December, 1967 and November, 1968 ATSF 7513 Built as ATSF 7513 in July, 1969, part of a single order for 20 units. All were retired in December, 1980, and sold for scrap to Precision National Corporation of Mt. Vernon, Illinois.Only 52 U23C’s were built for the US market, most of the rest were built by GE do Brazil for their domestic market. Santa Fe had the largest fleet: ATSF 7500-7519 (20 units) Penn Central 6500-6518 (19 units)Chicago Burlington Quincy 460-468 (9 units)Lake Superior Ishpeming 2300-2304 (5 units)The U23C used a 2300 hp 12-cylinder FDL engine in place of the 3000 hp 16-cylinder used in the U30C. It was intended for heavy, slow speed service where the extra horsepower of a U30C would not be utilized, while delivering greater fuel efficiency from a smaller prime mover. It was a competitor to EMD’s 2000 hp non-turbocharged SD38 and their 2300 hp turbocharged SD39.Santa Fe used theirs on their Eastern and Western Lines, primarily in New Mexico, Colorado and Kansas.