Built from 1895 onwards, these versatile flat bed wagons were used for a variety of traffic. Five hundred were built to 4 lots between 1895 and 1910. There were two versions: firstly, an 8T wagon with grease axle boxes and single side brakes (D336, 3 lots of 100 each, built 1895-9); and secondly 10T with oil axleboxes, heavier duty springs and independent either side brakes (D336a, 200 built 1910). It is likely that many D336 wagons would have been fitted with either side brakes during overhauls, and perhaps oil axleboxes.
Originally intended for agricultural machinery, they were used to transport a wide range of machinery, road vehicles, containers etc. The long low was a long-lived wagon with many examples lasting till the 1950s, and at least one survived in departmental use until 1961.
A choice of axleboxes and extra brake gear is provided so that this model may be built to represent a wagon in either D336 or D336a condition.