Detroit Diesel Corporation (DDC) is an American diesel engine manufacturer headquartered in Detroit, Michigan. It is a subsidiary of Daimler Truck North America, which is itself a wholly owned subsidiary of the mulitinational Daimler Truck AG. The company manufactures heavy-duty engines and chassis components for the on-highway and vocational commercial truck markets. Detroit Diesel has built more than 5 million engines since 1938, more than 1 million of which are still in operation worldwide. Detroit Diesel's product line includes engines, axles, transmissions, and a Virtual Technician service. Detroit engines, transmissions, and axles are used in several models of truck manufactured by Daimler Truck North America. Divisions Detroit Diesel consists of manufacturing operations of axles, transmissions and diesel engines for on-highway only, which is owned by Daimler Truck AG. The former off-highway division was sold to MTU Friedrichshafen in 2006 and subsequently purchased by Rolls-Royce in 2014. Detroit Diesel Corporation timeline January 1938: General Motors began diesel engine manufacturing in Detroit under the Detroit Diesel Engine Division, and re-organized its Winton Engine Corporation as the Cleveland Diesel Engine Division. Cleveland Diesel produced larger diesel engines for locomotive, marine, and stationary use. Detroit Diesel started production with the smaller mobile Series 71 two-cycle engines that the GM Research Division had recently developed. GM formed the General Motors Diesel Division (GMDD) as a marketing and customer service structure for its Detroit and Cleveland diesel products. 1939: Series 71 engines installed in buses manufactured by Yellow Coach (acquired by GM in 1943). World War II: Tanks, landing craft, road building equipment and standby generators needed compact, lightweight, two-cycle engines. By 1943, Detroit Diesel employed 4,300 people, more than 1,400 of them women. Together, these employees produced 57,892 engines in 1943. Detroit Diesel launches Series 110 engines used in construction equipment, rail cars, and power generation. 1950s: Wide use of GM's Detroit Diesel engines in military applications aided their acceptance in commercial applications. Detroit Diesel developed heavy-duty engines for long-distance trucks. GMDD began to develop a worldwide distribution network of independent, authorized distributors and dealers to provide parts and service for Detroit and Cleveland Diesel products. 1957: Detroit Diesel introduced the Series 53 engine, and put the Series 71 engine into use for both on-highway and off-road use. All engines within a Series were designed so that a vast majority of parts were interchangeable, facilitating production of many models of various horsepower by adding cylinders.