Robert,
(1) find engine/chassis number stamped onto the top of the right hand chassis rail, adjacent to the front engine mount cross member.
(2) go to
https://www.awm.gov.au/collection/AWM126/
(3) start trawling in the AMF (not AIF) series for 1941 Ford 3 ton lorries and match the chassis number to the chassis number in the register, which will provide you with the Army registration number, and possibly some disposal details. (I doubt very much it would be in the AIF series unless it is one of the 'transfers', so best to start with the most likely series).
The vehicle was in use in Australia on or after mid 1942 when the underbonnet nomenclature was introduced.
Nice find - very nice indeed!
Mike
