Coupling code: White Circle
Underframe: 64ft 6in
Engines: AEC 150hp
These vehicles were an updated version of the Swindon 79xxx cars built for the Edinburgh - Glasgow services for use on the Glasgow - Ayrshire / Stranraer lines. They worked these services almost exclusively until the early 1980s, when withdrawal came due to them being non-standard and the line scheduled for electrification.
They were 3-car sets with two cab types, one having a gangway to allow through access in a 6-car formation.
Although both batches had the white circle coupling code, there were considerable differences in the control system between each type; the first had an adaptation of the yellow diamond system, the second was essentially identical to blue square. The Swindon Inter-City (including the Class 123s) and Trans-Pennine vehicles differed from all other DMUs by having buckeye couplings and Pullman gangways.
The last vehicles were withdrawn in 1983, a three-car set survives in preservation.