During their life in government ownership, members of the 73 Class were at various times based at Eveleigh (Sydney), Delec (Sydney), Yeerongpilly (Queensland), Goulburn, Port Kembla, Queanbeyan, South Grafton, Taree, Cootamundra, Albury, West Tamworth, Orange, Dubbo, Parkes, Lithgow and Broadmeadow (Newcastle). Metropolitan yards such as Sydney Yard and Darling Harbour would often have a number of the class at work simultaneously. Class members were equally at home working trip trains in pairs around the metropolitan area to locations such as Botany, Cooks River, Flemington Markets and various mills. At many country centres, the 73 Class yard shunter would spent countless hours each week making and splitting up trains. In Newcastle, 73 Class units would operate to most sidings and yards, including to Sulphide Junction, Kooragang Island, Newcastle station and Port Waratah. Quad 73 Class worked a coal train on the Belmont branch on one occasion. On occasion in the 1970’s, 73 Class were used in multiple at Menindee and Hexham to assist trains through floodwaters.

The units are powered by a Caterpillar D379 V8 turbocharged engine, producing 700HP, with 650HP available for traction. The locomotives are 12.0 metres long over buffers, and weigh 49.8 tonnes.

7330 was the first locomotive to be withdrawn from government service, and this occurred in 1987. Many of the class were sold off and converted to 2 feet gauge to work on cane tramways in Queensland. 7301 was repainted into a CountryLink livery and worked as the Meeks Road shunter and hauled XPT cars around Sydney for many years. A number of other class members were transferred into private ownership, and still exist today. Such units include 7307 & 7321 with Patrick, 7333 & 7334 (the latter in CRT colors) with QRNational, and 7340 with Manildra at Narrandera.