The Marx 666 Engine Train Tender Penn Central Tender O gauge O27 Vintage Works is a vintage O gauge electric locomotive from the United States. This multicolored tin locomotive features a three-rail system and is powered by AC. The tender unit is a part of the model railroad’s collection, perfect for enthusiasts of classic trains. Marx’s attention to detail and quality craftsmanship make this locomotive a sought-after piece for collectors of vintage model railroads.