The GM class designates diesel-electric locomotives built by Clyde Engineering for the Commonwealth Railways. They were based on the EMD F7 and the class designation stood for “General Motors”. The first eleven built in 1951 had an A1A-A1A wheel arrangement to keep the axle load within limits for Australia. They were powered by a 16-cylinder 567B engine that delivered 1,500 hp. The following 36 locomotives had traction motors on all six axles. Power now came from a 567C engine with 1,750 hp. The last eleven, built in 1967, had dynamic brakes. 

In 1975, all came to Australian National. Some changed their operator again and a few were even rebuilt from standard gauge to 5 ft 3 in or 1,600 mm. Withdrawals began in 1988 and by 1994, only 15 were still in service. But even in the 21^st century, a number are still in service with grain trains for Aurizon and with Southern Shorthaul Railroad.