The RP-210 was a streamlined, 1,000 hp (750 kW) locomotive built in 1956 by Baldwin-Lima-Hamilton, specifically to operate with the lightweight, all aluminum, Train-X train produced by Pullman Car Company. This model represented Baldwin's attempted entry into the lightweight locomotive market, but only three of the low-slung units were produced: the first unit was built for the New York Central Railroad for use with their Xplorer train, and a pair was purchased by the New York, New Haven and Hartford Railroad for their Dan'l Webster train (New York, New York to Boston, Massachusetts).