Previously designed vans such as the JLX and other earlier designs had used a deep underframe which supported the walls and roof which made them heavy and difficult to maintain and repair.

The KLV's used a new integral design in which a lighter underframe was used and the walls and roof were all part of the structural strength of the wagon making them lighter, stronger and the non-moving parts virtually maintenance free.

Large doorways with a simplified latching mechanism were included in the design to enable loading with a forklift two standard pallets wide. Goods loaded included fruit and vegetables, cement, white goods, pet foods and just about any other palletised loading.

These vans were also used for the transport of large newsprint rolls in block train loads of up to 20 wagons from Ettamogah paper mill near Albury, conveying the loading to Brisbane.

The NSWPTC must have been impressed with the KLV wagons as a further 150 KLY vans were ordered in 1975 to an almost identical design, the only difference being louvers from top to bottom as opposed to the KLV's which had a plain centre panel. The KLV's were painted PTC Blue when delivered and were recoded KLY from 1974 onwards as 2CM bogies were fitted. The fitting of 2CM bogies saw the vans running in parcels traffic on passenger trains. In the 1979 four letter recoding they were recoded to NLKY.

In the SRA era of the 1980's some KLY's were painted SRA red and the entire NLKY fleet was transferred to National Rail ownership in 1994/95. NLKY's were recoded RLSY for Sadleirs traffic. Some RLSY wagons were painted light green, while commencing in 2005 some vans have been painted Pacific National blue with Pacific National logos.