The New Haven acquired 40 RDCs in 1952 and ‘53 and referred to them as “Shoreliners.” Twenty-nine were RDC-1s (passengers only), two were RDC-2s (baggage compartment at one end), six were RDC-3s (passenger, baggage and mail sections), and three were shorter RDC-4s (baggage and mail only). At the time, the New Haven was the country’s largest user of RDCs, running them mostly on branch lines and in commuter service. They were powered by two 275 HP General Motors diesel engines mounted below the floor, air-conditioned, and could accommodate 89 passengers. Many of these cars lasted until the New Haven was absorbed into the Penn Central in 1969. New Haven Railroad Budd RDC 47 was photographed at the Danbury (CT) Railway Museum – June 1, 2017.
Many of the New Haven's RDC fleet ran during the Penn Central years; at first in NH paint, then later on with Penn Central lettering on the sides and New York Central-style "fright stripes" on the end. The ex-New Haven RDCs often continued to sport the New Haven air whistles, though.