..... but it's enough, Tony, to fairly confidently say that you have one of the wholly imported early (to Australia) batch of cab 13 Ford Canada F15's (my first truck - ARN 55401 - was one of these, too). Therefore, it was assembled and then overpainted with KG3 from a partially knocked down kit which included a 2C1 body and Canadian type spare wheel carrier. These were a stop-gap measure to tide Army over until local manufacture of parts and local assembly of combination Aust/CDN parts into complete trucks geared up. Army wanted 4x4s, but all that was available at that stage from CND was 4x2.
The roof sounds like it has been 'disturbed' so may not be a good indicator, but should still have the standard slide type 1/2 steel rear 'window' rather than the canvas flap and fittings for same (even if removed, it will be obvious which one was fitted by the holes that are left). Rifle buckets should therefore be timber with rounded ends, held in to the floor by two large screws: often the pair of buckets were retained rather than having the passenger one replaced with a felt-lined steel box for the BREN butt, as per later Aust requirements. Roof to cab back bolts would be std UNC (Aust roof held to Aust back with Whitworth bolts: you'd know if this was the case, as you'd have to rat around looking for a b******y spanner that fitted when you pulled it off!)
There will not be a stamped engine number in the position indicated in my last post: that was purely on Australian Ford-assembled vehicles from parts supplied both from local and imported (CDN) manufacture. It also explains why the engine number was stamped on the gearbox, as per CDN practice.
The roof hatch, if you choose to reinstall it, will be of the CDN type, with shaped wooden fillers between the curve of the roof and the flat of the hatch base. It would have been bolted into place. Hatch is fabricated with an integral single piece 'panic handle'. (Aust Ford hatches were pressed steel, two main parts, a different size and welded into the roof, with a handle base welded to the roof forward of the hatch which mounted two std hardware handles, riveted to the base).
There should not be any holes in the left side of the cab for the gallows-type LAA mount (holes in both the cab rear panel and the roof panel). Again, these came later and were not generally retrofitted to these earlier CDN supplied trucks.
If the above applies to your truck, it supports my contention that this is a wholly CDN 4x2. They are a nice truck, and, as Rick C said, a White crown wheel and pinion fitted into the original diff housing does good things for their road speed.
Best regards
Mike C