With the ongoing introduction of diesel locomotives to the New Zealand railway network, various options to replace steam traction in the South Island were investigated.

A World Bank modernisation loan was obtained in December 1965 for a four-year term to December 1969, allowing the Cabinet Works Committee in February 1966 to call tenders for 55 1,000-1,200  horsepower diesel locomotives for the South Island, and 34 locomotives of 1400-1600 horsepower to complete North Island dieselisation.

[2] In addition, five of the English Electric DI class locomotives were already in service with NZR at the time and were the prototype for the tender specifications.

[5] The World Bank, the pressure to accept one of the low Japanese tenders,[6] was not out of any preference for a specific manufacturer, but out of growing dissatisfaction in Washington by the administrations of Lyndon B. Johnson and later Richard Nixon for the use of the World Bank development loans for infrastructure projects in advanced nations.

The Minister of Finance, Robert Muldoon, clashed with United States' officials regarding New Zealand's use of the World Bank,[7][8] the World Bank, therefore, financed only low tenders which delivered locomotives quickly to complete conversion of NZR to diesel traction at the earliest date possible.

When working in multiple with these classes, it was common practice to have the DJ as the lead locomotive due to its superior cab conditions and visibility.

Eventually, steam heat vans were transferred from the North Island Night Limited when the Silver Star was delivered a year late in November 1971.

With fewer stops, the DJ class hauling the lighter, 200 ton eight carriage Southerner offered a slightly higher stop-to-start average speed than the steam-hauled South Island Limited, with 47 miles (76 km) average speed between Ashburton and Timaru and between Ashburton and Christchurch.

On the Picton Express the DJ class cut running times by more than an hour, on the steep route with three 1/35 grades in 1976-8 and hauling loads of up to 250 passengers.

The greatest improvement offered by the DJ over the JA class steam locomotives was in hill climbing particularly on the Greymouth-Otira section of the Midland line and in moving heavy slow freight.

Due to their light axle loading, no major track upgrades had been required to allow the DJ class to enter service in 1968.

The last DJ-worked Southerner service took place in June 1990 although one final instance was recorded in February 1991 when a DJ hauled the train from Invercargill to Dunedin.

[24] After New Zealand Rail Limited took over running of the ORB line in 1991, DJ3303 was placed in storage before being sold for preservation to Mainline Steam.

Ten of the class were also moved to Hutt Workshops in 1990 for storage as a back-up in case of traffic increases or failures of other locomotives, or possible sale to other buyers.

[28] In 2000, the locomotive was allocated to Whangārei, for use in Northland, including working the Dargaville Branch,[29] and the Portland-Port Whangarei wood chips circuit.