vehicles. The technical description of the formation was BDTS+MLV+TC+DTS. Individual carriages were numbered as follows: 75920-75928 - BDTS 68011-68019 - MLV (68011 - 68014 from units 313-316 converted to MBSO in 1971 and renumbered 62431–62434. Units reclassified as Class 308/4) 70644-70652 - TC 75953-75961 - DTS When Tilbury Docks closed as a cruise liner terminal, these units were made redundant and withdrawn from service in 1983. Three units were subsequently rebuilt as Class 308/4 parcels units for Rail Express Systems (see below). Class 308/3 Finally, a third batch of 3-car units were built in 1961 for suburban services from London Liverpool Street to and . They were numbered 453–455, following on from the Class 305/1 units, which also operated these services (which were numbered in the range 401–452). These units were later reclassified as Class 308/3, and renumbered 308453–455 under TOPS. Unlike the first batch, these units contained no first-class seating. Each unit was formed of three carriages: two outer driving trailers, and an intermediate motor coach. The technical description of the unit formation was BDTS+MBS+DTS. Individual carriages numbers were as follows: 75741-75743 - BDTS 61689-61691 - MBS 75992-75994 - DTS These units were withdrawn in the late 1980s. Converted postal units In 1983, three former Class 308/2 units (nos. 314/319/321) were converted into Class 308/4 postal units by the Parcels sector, with the removal of the intermediate trailer, and renumbered 308991–993. These units were replaced by three converted Class 302/9 parcels units in 1992. Operations By the early 1990s, only the Class 308/1 units were still in service. These were gradually replaced on GEML services by the new Class 321s. Some of the displaced units were transferred to the London, Tilbury and Southend line (LTS), whilst others were transferred to the West Midlands to work Cross-City Line services pending the introduction of new Class 323s. The LTS units were later displaced by Class 312s, but two were retained and converted to Class 937 sandite units. These sandite units were originally fitted with a small cement mixer that was used to mix the sandite and then loaded into the hoppers whilst the vehicle was in motion. Later, premixed sandite was loaded prior to use with the easing of the physical work by the staff. In 1994–95, electrification spread north from to Bradford, and . As no new stock had been ordered, Regional Railways overhauled Class 308 units for use on