Hi Paul,
Very nice straight example. Nice find indeed. There is a companion to this truck (same number block) in the AWM collection in Canberra (but I cannot locate the entry for it on-line).
s/n 91024778 is almost certainly somewhere in the Army registration number block from 120801 to 121834. I've got all manner of s/ns around it (including 91024780), but have not got that particular s/n listed.
The truck is a standard T110L fitted with 10.50x16 chevron pattern bar tread tyres which were a general use military tyre and not peculiar to desert applications. It was assembled in Australia - it has the Australian timber tray body and POW can boxes, and Aust Army pressed steel (two piece) roof hatch with top-hat section grab handles rail, and the cab fittings for the .303 inch BREN LAAMG mount on the cab rear left corner. I suspect you'll find the fitting to stow the BREN in the cab, if not, then certainly the mounting holes. It' s also still fitted with CMP-type black out driving 'spots' on the lower edge of the front mudguards.
Altogether, a really,
really nice example and appears from your images to be very original. So congrats!
When you are able and if you wish to, post the engine number and we'll see if it can be traced via that way. Otherwise, carefully sand off the rounded face of the bonnet & nose on each side: the reg number should be under that top-coat of paint, in white numerals about 3.5 inches in height.
Mike