British Rail Class 66

References to "UIC II" and "EU Stage IIA" relate to emissions control regulations set by the UIC and EU, respectively. In general, and without regard for subsequent modifications, locomotives ordered before 31 December 2002 will be original specification, while those ordered after that date will be either UIC II or EU Stage IIA specification.

The British Rail Class 66 is a type of six-axle diesel-electric freight locomotive developed in part from the Class 59, for use on UK railways. Since its introduction the class has been successful and has been sold to British and other European railway companies. In Continental Europe it is marketed as the EMD Class 66 (JT42CWR).