Hi Bill,
It looks as though the chassis has been lengthened, between the axles and I think that I can see some bolts in the chassis between tank and cab, is there a piece been let in there? The front propshaft looks longer. The reason some QL's have two tanks was that the bodies were right up to the rear of the cab, there fore the standard tank and wheel carrier on a QLD cargo could not be used and twin side tanks were used on certain models. That brass palte is a postwar fitment giving the post-1948 army number at the top. This might be traceable at the RLC Museum, Deepcut. The chassis number on the plate does not point out what body type was fitted, you will find the chassis number stamped on the passenger side of chassis just behind the cab, on vertical face. It will start, QL, then next letter could be D, R, C, depending on the version.
Richard