These E.M.D. diesel- electric locomotives entered service in October 1967. They featured increased traction power and wheel slip control performance through the use of the model 645 engine, AC main generators and DC traction motors. Clyde has placed 303 second generation locomotives in service with Australian Customers.

The introduction of third generation diesel-electric locomotives in July 1980 heralded the single greatest advance in locomotive technology. The productivity of diesel-electric locomotives was revolutionised by the use of the super series wheel creep control system, in conjunction with the turbo-charged model 645 diesel engines, AC generators and DC traction motors. Clyde has placed 118 third generation locomotives in service with Australian Customers.

The fourth generation entered service in March 1988. This generation continued the productivity gains of the third generation locomotives with higher efficiency as well of offering considerable maintenance advantages. These advantages were through the use of the microprocessor based E.M.D. 60 series control system. This system included significant diagnostic features and was used in conjunction with the E.M.D. model 710 diesel engine, AC main generator and DC traction motors. Clyde has placed 145 fourth generation locomotives in service with Australian customers.

The fifth generation of Clyde G.M. locomotive, (the first of which will become "4000" class currently on order by Queensland Rail),will begin service in late 1999. It features the new radial steering bogies, 2424 kw (3000hp) 12 cylinder 710G3B engine using EMDEC fuel injection for optimum fuel efficiency and emission control. An EM 2000 microprocessor control system and Siemens AC traction systems will ensure the continuous adhesion levels of up to 37 percent. The new locomotives will be the most powerful narrow gauge diesel-electric locomotives operating in the world to-day.