As originally built, the DM class motor cars had a second driver's cab located in the luggage compartment at one end of the car allowing them to operate as single car units. The second cabs were progressively removed to provide spare parts giving increased luggage space. Prior to this, the all-night service on the Johnsonville Branch was operated by one of the 1942 stock DM cars, an arrangement which was considered for use on a similar service on the Melling Branch.