Coupling code: Blue Square
Underframe: 57ft 6in
Engines: Rolls Royce 180hp
These sets were built to operate services on the former Lancashire and Yorkshire main line, and spent their entire careers based around this same area. This earned them the name of the 'Calder Valley' sets. This arduous route meant they needed a bit more power than most sets, so they were fitted with 180hp Rolls Royce engines, and when delivered they had the best hp/ton ratio of any of the DMUs, including the lightweights.
The first twenty sets were ordered for the NER, the second batch (ten sets) for the LMR. Deliveries of the two batches was concurrent, and these were the penultimate Class of first generation sets to be built. They were an updated version of the Class 104, with a revised cab design and alloy window frames.
Each set had 24 first class and 159 second class seats.