Originally built as 2-car units in 1987 – 1988, these vehicles were converted to single cars at Hunslet-Barclay a few years later. Since then they have been in great demand for use on lightly loaded services and for strengthening other units at busy times. They have an unusual riveted body panel structure on a steel underframe with single-leaf Bode doors. The panel construction eases the repair of any damage, panels being standard Leyland National Bus parts.. The power train is the dependable Cummins-Voith Gmeinder combination, the engine being the Cummins NT855, providing 285 hp. Couplers are the BSI standard, enabling full multiple working with class 14X, 15X and 17X “Turbostar” units, and a gangway is provided to connect with class 150/2 and 156 units.