The Electro-Motive Diesel (EMD) Class 66 (or JT42CWR) are Co-Co diesel locomotives built by EMD for the European heavy freight market.Designed for use in Great Britain as the Class 66, a development of the Class 59, they have been adapted and certified for use in other European countries. Outside Europe, 40 locomotives have been sold to Egyptian Railways for passenger operation.A number of locomotives built for Euro Cargo Rail in France with roof-mounted air conditioning are classed Class 77.