The 48 Class were A. E. Goodwin’s response to a NSW Government tender for twenty branchline diesels in 1958. A further ten units were ordered in 1960, followed by another fifteen units in 1961. The first forty-five members of the class are referred to as “Mk1″ units. Based on the success of these first class members, another forty units  were ordered in 1963, to be known as “Mk2″ units. The NSWGR ordered another forty units in 1965 (Mk3), with a final forty 48 Class ordered in 1968 (Mk4), ensuring the class totalled 165 locomotives.

Seven 48 Class locomotives were converted to PL (PortLink) class in the late 1990′s, specifically for push-pull container trip trains in the Sydney metropolitan area, although the class is arguably better known for recent work on coal trains in the Newcastle area. For more details on the PL Class, see below.

Many of the Mk1 48 Class were withdrawn in the 1990′s and sold to private operators, although the remaining members of the class were included in the sale of FreightCorp to form Pacific National. The surviving Mk1 members of the class are split between Junee Railway Workshops and Engenco (formerly Coote Industrial) for lease service, while RailCorp maintains 4819 and 4827 for shunting and infrastructure work. The remaining surviving locos from the Mk2, Mk3 and Mk4 groups are split between Pacific National and GrainCorp. A number of Mk1 units are also preserved with various groups.

Mk1: 4801 - 4845.

Mk2: 4846 - 4885.

Mk3: 4886 - 48125.

Mk4: 48126 - 48165.

Source: Trackside