train number was displayed on an LED on the driver's desk. In the old trains the number box was integrated into the driver's door. The 1972 Mark 2 trains first operated on the Northern line alongside the 1972 Mark 1 trains. In 1977, they were transferred to the Bakerloo line and operated alongside the 1938 Stock until the opening of the Jubilee line in 1979. In 1989, several Northern line units were painted in experimental liveries, and three trains were internally refurbished, before the refurbishment work was stopped because of the decision to order a new fleet. 3227 and 3518 were painted with blue doors and a white body, 3204 and 3522 were painted with a blue and white body, and 3202 and 3523 were painted in what would become a corporate livery. With the introduction of the 1983 Tube stock on the Jubilee in 1984, half of the 1972 Mark 2 trains were transferred back to the Northern line. After the introduction of a second batch of 1983 Stock on the Jubilee in 1987, all 1972 Mark 2 trains on the Jubilee and Northern lines were transferred to the Bakerloo line, where they remain in service. The earlier (Mark 1) 1972 stock on the Northern line was replaced by 1995 Tube Stock in 1999. After being withdrawn from the Northern line, a few cars of 1972 Mark 1 stock were converted to run with 1967 stock in service on the Victoria line. A further two trains were converted to be compatible with the Mark II type, and these now run on the Bakerloo line. One ex-Northern line set (3229) was based at the now-closed Aldwych station, for use in films until being sent to Ealing Common Depot in November 2021 and then Ruislip Depot a month later. Another Mark 1 unit in a trial livery was sent to Acton Works to be used for shunting. One three-car unit (unit 3511) used to reside at Hainault depot until October 2018, where cars 4511 and 3411 had moved to Acton Works. The cab of unit 3511 had been used onto unit 3538 following collision damage. The 1972 trains are formed of seven-car sets and have a total of 268 passenger seats. After withdrawal from the Northern Line, five four-car units (units 3201, 3208, 3211, 3212 and 3230) were considered for use on the Waterloo and City line. The objective was to