The K2/Y could take ten casualties sitting or four stretcher cases. The rear body, known as No. 2 Mk I/L was developed by the Royal Army Medical Corps and built by coachbuilder Mann Egerton. Simple canvas closures were used in place of driver's cab doors.
The interior dimensions were approximately 2.6 metres long, 2.0 metres wide and 1.7 metres high. At the rear of the vehicle there were two large doors. From the driver's cab the wounded could also be accessed through a small internal door with a seat. The exterior was mainly made from painted canvas.
The Austin K2/Y was generally regarded as having a widely spaced four-speed gearbox that needed to be "understood", but once mastered provided good service. It had two petrol tanks, one on each side (total capacity: approx. 2×12 Imperial gallons (2×54.5 L)). The top speed was around 50 mph (80 km/h).
A total of 13,102 Austin K2/Y ambulances (the front mudguards ended at the 'doors') were built at the company's Longbridge plant almost continuously from 1940 until the war ended. An estimated 50 or more remain today. The Austin chassis was one of three main designs fitted with Mann Egerton bodies, the others being Morris Commercial CS11/30F (the front mudguards ended underneath the rungs) and Bedford ML 54 (the front mudguards ended before the 'doors'). It is estimated there are two remaining Morris Commercials, but no Bedford examples are said to survive