The 600 & 700 Class Railcars are a Diesel Multiple Unit train built by New South Wales Government Railways (NSWGR) primarily on regional lines throughout NSW. The trains have since been phased out in favour of the newer Endeavour railcar model. The 600/700 railcars were built by NSWGR between 1949 to 1950 at their Rolling Stock Workshops, Chullora, NSW. These trains are a 2-car unit consisting of a driving power car and a driving trailer car.

The power cars were fitted with two 165 horsepower General Motors Detroit Diesel in-line six-cylinder, two-stroke diesel engines coupled to Allison hydraulic transmissions. The 600's were capable of multiple unit control within the class only and trains of 8 cars (four 2-car sets) could be operated.

The ten units were initially deployed on lines throughout country NSW including Queanbeyan to Bombala, Dubbo to Bourke, Cobar, Coonamble and Gwabegar, Armidale to Glen Innes and services based on Cootamundra working to Lake Cargelligo and Tumut, Werris Creek to Gwabegar, Moree and Walgett and Wallerawang to Mudgee. With the introduction of the DEB railcar, a number were displaced from their regular working and some of these units sent to Newcastle for suburban working, while others remained on other country routes.

The 600 Class were incompatible electrically with the later rail cars of the 900/950 and 620 Class. In 1972, NSWGR purchased 22 Cummins diesel engines and Twin Disc transmissions with the intention to re-engine the entire class. However, repeated failures amongst the early 620 Class units resulted in the diversion of some engines and transmissions for 620 Class re-engining and in the end only five of the ten sets were converted to 660/760 Class units between 1973 and 1975.

In the 1980s, the remaining five unconverted sets were sent to Blacktown to work the Richmond Line. Many problems were experienced with starting due to the need to shut the engines down to reverse and they were fitted with air starters in place of the more normal electric type. All sets were withdrawn following the electrification of the Richmond Line in 1991.

The 600 Class were the first in a long line of 92 vehicles built between 1949 and 1968 to the same basic design. The 600's were followed into service by the air conditioned main line DEB Railcars from 1951 and the 620 Class 2-car suburban units from 1961.

Of the remaining five sets (ten cars), five cars were scrapped (two following their partial destruction for an episode of the ABC television series Police Rescue in February, 1992) and four were sold to the Rail Motor Society at Paterson, New South Wales. CT 602 was burned out by vandals at Mortdale before transfer the Rail Motor Society. The partially stripped body shells of 604 and 704 were given to the Society in compensation and after further stripping of parts they were later sold to the local Court House Hotel at Paterson for accommodation. The remains of CT 702 was scrapped and the other three cars (WFP 602, FPH 606 and CT 707) all survive in near original condition in the collection of the Rail Motor Society.