The KAB wagons were converted from _T__ and _U__ long wheelbase vans. Twenty one wagons were converted, numbered 1 - 21.
Traffic was from the Rosedale, Victoria, Pineboard factory to Montague, Melbourne. Pineboard is made from pulped woodchip which is processed to a pulp then pressed rolled into sheets for interior construction, wall covering, etc.
The class was withdrawn from service in the early 1980's. Some wagons were re-used and converted to KMQ_.