The class was a new design for Australian conditions based on other locomotives produced by Downer EDI Rail, such as the narrow gauge GT42CU AC purchased by Queensland Rail and Pacific National and the GT46C purchased by Westrail, Freight Australia and FreightLink.

[1] With the ageing of the 48 and PL-class fleets, Pacific National purchased 31 TT class locomotives for Hunter Valley traffic.

The first locomotives were originally intended to be built as LDP010-LDP018 and leased to other railway operators, until Downer EDI and Pacific National reached an agreement to sell directly.

Operated by Pacific National, they are used to haul coal trains from Whitehaven's mines in the Gunnedah Basin.

Numbered GWB101 to GWB103, they were deployed on intermodal, grain and ore traffic and were included in the sale of One Rail Australia assets to Aurizon in July 2022.

These locomotives arrived on Australian shores on 24 January 2023, and entered service in March of the same year.

On 14 June 2023, GWA003 and ALF21 collided with a truck near Katherine and subsequently caught fire, GWA003 and ALF21 were destroyed and subsequently Scrapped[12] The first two class members were originally built as LDP013 and LDP014 in 2013, they were then purchased by Southern Shorthaul Railroad in 2014 to operate on their Weston Milling grain service.

Southern Shorthaul Railroad ordered two GT46C ACe Gen-II locomotives in 2023, they entered service in early 2024.

In an agreement similar to CBH Group's contract with Aurizon, beginning from 1 November 2024, Southern Shorthaul Railroad will provide train crews and oversee daily operation of Manildra owned locomotives and wagons.