Alco RSD7 Builder List and Phases

RSD7 Roster Index


  • Phase I – January to February, 1954 – Alco Specification DL600. Two 2250 horsepower prototypes were built, Alco DL600 and DL601. They had General Electric GT586 main generators, GE752 tractions motors, and Alco’s turbocharged 16-cylinder 244G engine. They introduced the new carbody style that would be carried forward to the RS11, RSD12, and RSD15. The same Tri-Mount truck used on the RSD4 and RSD5 continued to be used, with single shoe brakes and two air cylinders per truck. Both air tanks were mounted one above the other on the same side of the fuel tank. Sand filler lids were square.
  • Phase IIa – October, 1955 to January, 1956 – Alco Specification DL600A. These production units were built with the 16-cylinder 244H engine, and were rated at 2400 horsepower. They were a foot and a half longer than the two prototypes. Sand filler lids were now round instead of square. Phase IIa units have clasp brakes with four air cylinders per truck instead of two.
  • Phase IIb – February to April, 1956 – Brake wheel is moved from inside the cab to a round recessed location on the front of the short hood.


Pennsylvania units had a pair of open boxes behind the cab on the engineer’s side of the unit for Train Phone and automatic train stop equipment.

Builder List

YearMonthRailroadOrder NoBldr NoPhaseQty
1954JanuaryAlco DL600
- ATSF 600
1954FebruaryAlco DL601
- ATSF 601
1955OctoberATSF 602-606S323681106-81110IIa5
1955OctoberATSF 607S323681121IIa1
1955NovemberATSF 608-611S323681122-81125IIa4
1955DecemberPennsylvania Railroad 8606-8608S325781745-81747IIa3
1956JanuaryPennsylvania Railroad 8609-8610S325781748-81749IIa2
1956FebruaryChesapeake & Ohio 6800-6802S326881901-81903IIb3
1956MarchChesapeake & Ohio 6803-6810S326881904-81911IIb8
1956AprilChesapeake & Ohio 6811S326881912IIb1


  • John D. Hahn, Jr., Pennsylvania Railroad Diesel Locomotive Pictorial, Volume 1: Alco RS Series, Withers Publishing, 1995, pgs 47-48
  • Kenneth L. Douglas and Peter C. Weiglin, Pennsy Diesels 1924-1968: A-6 to EF-36, Hundman Publishing, 2002, pg 148-149
  • Jerry Doyle, Chesapeake & Ohio Diesel Locomotives in Color 1949-1971, Chesapeake & Ohio Historical Society, 2006, pg 75
  • Chesapeake & Ohio Diesel Review, The Chesapeake & Ohio Historical Society, 1982, pg 178
  • John F. Kirkland, The Diesel Builders, Volume 2: American Locomotive Company and Montreal Locomotive Works, Interurban Press, 1989, pg 150-152
  • – AT&SF RSD7 roster
  • Robert Lehmuth, American Locomotive Company Complete Works – Volume 8, pg 40, 49, 80, 99-100