Intended for use with the Airfix Stalwart Mk.2 and SMM3570A 
PLEASE NOTE: Although this set concentrates on the crane, the Atlas photo-etch logo is ONLY included in the SMM3570A set, for which this set is intended. You will also have to do major surgery on the Airfix cab to fit the grilles, if you do not use the SMM sets.
The Stalwart was a front-supply High-Mobility Load Carrier, an off-road truck that could follow and reach tanks and artillery units – capable of negotiating knife edges and the like, unlike normal trucks. They saw British Army service from 1963 (the Mk.1) until 1993. The role of the Stalwart was to get supplies to front-line units, usually in the dark. The swimming role of the Stalwart was only in case a bridge was not available. Swimming was not the primary role of the vehicle. 
All of the Stalwart Mk.2 (FV623) Royal Artillery Limbers were based on ET VRN vehicles. These all had rubber-sealed windows (no bolts) – apart from the rear side windows remaining bolted as they were used as escape windows that could be slid down – as per the Airfix kit.
ET VRNs predominantly had the cargo sideboard strengthening bar high up the side, with two small vertical bars connecting it to the top of the sideboard – also in the Airfix kit. When the RA Limber was designed, a third seat was mounted on the right side of the cab instead of the radio battery box mounts (from 1969). A right-hand passenger footplate was added, otherwise the passengers feet slid down the hull’s slope and interfered with the hand throttle. The seat and footplate can be found in the SMM3570A set. Some units retrofitted a third seat to standard Mk.2s when the Limber was released.
They started life with amphibious capability but, later in life, water jets and trim vanes were removed from many vehicles, but not all. All external openings were plated over.
ALL Stalwarts had antenna blanking plates on the cab roof. However, the Royal Artillery did not have radios in their crane versions. FV623 had four seats in the back and small protective pram-like tilts (each with 2 windows) either side of the crane (SMM3570D).