The B&O (Baltimore And Ohio) SD20-2 (not to be confused with the IC SD20) is a type of rare, six-axle, 16-cylinder, 2,000hp diesel locomotive rebuild built by the B&O railroad between 1979 and 1980 with only 5 built, and 1 (CSX #2402) currently remaining in a deadline awaiting to be scrapped. The sole-surviving unit is currently sitting on a siding next to a retired GE B30-7 (CSX #5552) in Essington, PA (near Philadelphia) at an industrial park.
CSX SD20-2 YN3

CSX 2403 prior to when all but one of the units were retired from the road in 1998.

All five original units were originally SD35's built in 1964, and were numbered 7700-7705, and eventually were renumbered from 2400-2405 upon the CSX merger. At some point, #7700 and #7702 swapped numbers as well.

The SD20-2 rebuilds were ultimately rebuilt with roots-blown 645E prime-movers and were fitted with "Dash 2" electronics rather than having their original 567 prime-movers with otherwise outdated, pure DC electrical systems found on models like the GP35.

Only one of the units built remain.


The B&O SD20-2 was initially meant to be part of a rebuild program which involved the rebuilding of earlier second-generation six-axle EMD diesels like the SD35 owned by the B&O portion of the Chessie System Corporation during the turn of the decade in 1979-1980. But because of financial concerns regarding the Chessie System corporation's interest in merging with their long-time neighboring railroad corporation Seaboard System (originally Family Lines System), things fell through, and the remaining SD35 units originally scheduled to be rebuilt as part of the program were simply retired and scrapped from primary service. All five of the original units served as heavy-duty hump yard switchers serving Queensgate Yard in Cincinnati, Ohio, but eventually found their way in local service and served other yard duties before they were soon retired and scrapped by CSX from 1998 to 2004, with #2402 having been the last to be withdrawn from the company's roster. One unit (CSX #2401), was sold to the Ohio Central Railroad (OHCR) sometime in 1999-2000, but was then acquired by the Pacific Harbor Line (PHL) where it remained until it was scrapped in 2008. 


CSX #2404 was involved in a side-swipe incident and had its cab rebuilt, yet was originally intended for scrapping for it was once deemed to be unsalvageable by some maintenance crews.

CSX #2402 is among one of the few surviving YN1-painted CSX units left in existence. As of 2016, all active units on the railroad's roster are painted in YN3b, YN3, YN2b (bc-y), or YN2 paint.