IBG Models make a QLR tractor and Wireless in 1/72 scale.
Looking at the parts RM would need to make them as an upgrade set, similar to the Opel body set....hay......must not get too far ahead of oneself, the RM workforce need a brake from work as well.
Just to ask....is the gun for early/mid war? I have seen a few American/Normandy photos that that have different styles of stabaliser arms that fold in for transport mode.