class and nineteen 850 class carriages were converted, becoming the 860 class. These steel cars had been built at Islington Railway Workshops between 1944 and 1946 as part of a plan to electrify Adelaide's suburban railways. For use with 348 to 373, thirteen 327 class wooden end loading suburban baggage cars were converted, becoming the 820 class trailers. These had been built between 1912 and 1924. The 400 class were used as single cars on the main lines during the evenings and at most other times on lightly patronised services such as the Grange, Tonsley and Northfield lines. They were also used in multiple with other 300 or 400 class units. These railcars became the backbone of the metropolitan services, relegating most loco hauled passenger trains to regional and interstate services. "Superchook" variant Following the introduction of the 2000 class railcars in 1980, two 300 class Redhens and an 860 class trailer were chosen for an experimental rebuild at STA's Regency Park workshops. Nos 300, 337 and 862 were modified in 1983 with new interiors, elevated cabs and stainless steel panelling similar to the 2000 class. The rebuilt cars were re-numbered 2301, 2302 and 2501 and entered service in June 1983. They soon acquired the nickname, Superchooks (a play on "Redhen" – a chook, in Australian vernacular, is a chicken) The exercise was not successful and no more were modified. The Superchooks saw only limited passenger service and often 2301-2302 was sandwiched in between two 400 class Redhens. They were withdrawn in 1992. Withdrawal All thirteen of the 820 class trailers were retired by December 1976. The corresponding 300 class Redhens were then coupled to a 400 class railcar to form 2-car trains (designated 300/400 class). In 1987, the steel-bodied 860 class trailers were withdrawn and all the 300 class Redhens were reconfigured as 2-car trains, usually consecutively numbered pairs. The first group withdrawal of Redhen railcars and 860 trailers occurred when 6 300 class railcars and 2 860 trailers were condemned in 1984, following the delivery of 30 2000 class railcars from 1979 to 1981. In 1987/88 the State Transport Authority introduced the first of its new fleet of 3000 class railcars, which were intended to replace the Redhens. As more 3000 class were delivered through the early 1990s, mass withdrawals of Redhens commenced and they were gradually restricted to operating only during weekday peak hours. This was especially