Harris trains were introduced in 1956. Trailer cars were numbered 601 - 690 (1st series) and 801 - 896 (2nd series).
For trials on planned new suburban trains, six trailers were built to 75' length, 15' longer than ordinary cars. The cars were numbered 891 - 896. Pairs of these cars were placed into three sets. Each set being the equivalent length of 7 1/2 'standard' length suburban trains. The sets were run on lines modified for eight car trains. Generally this was all lines except Pt Melb, St Kilda, Sandringham, Epping and Hurstbridge.
As the Harris car fleet was lined with asbestos insulation they were starting to prove a hazard by the late 1970's. Increased vandalism inside the cars exposed the asbestos to crews, maintenance and the travelling public. This exposure initiated industrial unrest to repair or withdraw the cars.
With more Comeng trains in service by the late 1980's, the Harris trains were withdrawn from service.
The majority of cars were buried in a large pit at Clayton; a cheaper option than industrial asbestos removal.
Comeng rebuilt some cars to 'Grey Ghost' _T__ cars. The railways also stripped about forty cars for interurban service. Four cars became railmotor trailers.