The bodies of the DE30AC and the DM30AC are extremely similar; the difference is the ability of the DM30AC to use electric third rail while the diesel engine is off, enabling the locomotive to use the East River Tunnels into New York Penn Station.

A few such trains a day run on the Port Jefferson, Montauk, and Oyster Bay branches, usually during peak times.

Due to their height, the DE30AC and DM30AC locomotives, as well as the C3 bilevel railcars that they typically haul, cannot fit through the 63rd Street Tunnel, and are thus unable to serve Grand Central Madison station.

In December 2020, the Metropolitan Transportation Authority of New York board approved a Federal Transit Administration-funded $335 million contract for 27 dual-mode locomotives, based on the Siemens Charger design.

[8][9] As a part of the Long Island Railroad's Capital Program, the railroad is exercising Option 3 of the previously awarded contract to order up to 44 new dual-mode locomotives, which would likely replace the older DE30AC and DM30AC locomotives.