All the TOPS classes changed in later years making all vehicles Class 101.
At some point vehicles E50246 - 8 were reseated in a 2+2 formation rather than 2+3. The vehicles were built for and delivered to South Gosforth for Newcastle suburban duties where 2+3 seating is required. They were later transferres to Darlington where the more roomy 2+2 seating was appropirate for the rural duties.
In 1983 saw the vehicles that were numbered in the 50xxx and 56xxx series renumbered in the 53xxx and 54xxx series respectively.
Two Class 101 trailer seconds were renumbered in 1990 from 59101 to 59110 and 59105 to 59111. This was to avoid clashing with the new Class 59 locos.
By the mid '80s almost all DMC, DTC & TC vehicles had been declassified to DMS, DTS & TS.
Most Regional Railways DMS and DTS vehicles were re-seated into a 2+3 configuration in the former first class sections, increasing capacity of each to 72.
During the 1980's vehicles allocated to Reading were fitted with additional luggage space for working Reading - Redhill services which serviced passenengers from both Heathrow & Gatwick. This reduced seating capacity by 12 seats per 3-car set.