According to James Mischke's Baltimore and Ohio Railroad Diesel Locomotive Roster, Second Edition, the B&O never acquired an RDC from the Long Island Railroad. They acquired one unit from the C&NW and another from ATSF. A third unit, the one you were likely referring to, an RDC-1, was one that was leased by the B&O, and which originally belonged to the New Haven Railroad, which was merged with Penn Central. The Penn Central sold this unit to a private firm, who leased it to the B&O. If I have confused you, here is the sequence of events:
1) RDC-1 bought new by New Haven RR as no. 40, in March, 1953.
2) New Haven RR merged with Penn Central on Jan. 1, 1969.
3) Same RDC-1 unit sold to J.F. Jones Properties of Tamarac, FL, in 1972.
4) Same RDC-1 unit leased by J.F. Jones to B&O as their #98 from Oct. 2, 1974 to April, 1976, when sold by J.F. Jones to SEPTA.
I tried looking for pictures, but wasn't able to find any.
Wade Rice
Member, B&O RR Historical Society
http://www.borhs.org
Daniel Willard (1860-1942) and Jervis Langdon, Jr. (1905-2004) - Two of B&O's best presidents and managers!
President Leonor Loree (1858-1940) brought the B&O into the 20th century!