The locomotives, built in 1971 and 1972, operated on all main lines in South Australia and interstate to
Broken Hill and
Melbourne. The first three were delivered on
broad gauge bogies and the latter three on
standard gauge bogies. All were initially delivered in the South Australian Railways' red and silver colour scheme. The three standard-gauge locomotives were soon repainted in the South Australian Railways' "mustard pot" colour scheme (yellow with brown lining and silver bogies). In 1975, 703 was damaged when a bridge at
Crystal Brook collapsed and was repaired at
Islington Workshops. During 1987, all six locomotives were transferred to broad gauge to cover a locomotive shortfall as the older
930 class was withdrawn. In 1994, 702 caught fire near
Blackwood and stored. It was intended to use 44221 as a parts donor for it, however both locomotives were scrapped in 1997. After the conversion to standard gauge of the
Adelaide-Melbourne railway line in 1995, all of the remaining 700 class were converted to standard gauge. In 1997, the remaining five units were included in the sale of Australian National assets to
Australian Southern Railroad. 706 was transferred back to broad gauge in 2000 to work on the daily
Penrice stone train. Several years later it suffered a mechanical failure and was not repaired; in 2022 its engine unit was sold to the Australian Locomotive and Railway Carriage Company and its (broad-gauge) bogies were donated to the National Railway Museum, to be placed under 703's body, which One Rail Australia had donated. 704 was transferred to broad gauge to replace it, running until 2014, when it was stored after the Penrice stone train service ceased. Locomotive 704 was donated to
SteamRanger Heritage Railway by One Rail Australia and delivered to Mount Barker in August 2022 for eventual revenue service. Locomotive 703, also donated by One Rail Australia, was delivered to the
National Railway Museum, Port Adelaide, in January 2023 as a significant display item and for shunt duties. Locomotive 705 was delivered to the
Steamtown Heritage Rail Centre in August 2023. ==Disposition==