The sign on the 1 ton Chev GS, as Tony mentioned, has the formation sign of a black swan on a yellow background, surmounted by a 1 inch wide white stripe across the top, which equates to 1st Aust Corps Troops, Middle East, while the Unit sign of '308' on a black background equates to any of the four (3,4,5,or 6) Anti-Malaria Control Units under command - they all carried the same sign. The design of sign with the combined formation/unit together, and the formation sign itself, were introduced on 12 January 1942. The black swan/yellow ground formation sign only applied to units in the Middle East.
Later, the name of the Anti-Malaria Control Units was changed to 'Aust Malaria Control Unit'.
The 1 ton with registration AIF V5252 was sent to the ME in October 1940, so had lasted very well given the image was taken in 1942. The Chev 3 ton GS reg L14045 went to the ME in June 41. The Cab 12 'Nancy' has a Brit registration - a common occurrence for CMPs issued to Aust units from British stocks in theatre, often with the letters 'AIF' simply prefixed to the Brit number. Can't quite see if that is the case with this truck due to the angle.
Thanks, Mike: nice pics. Lots of details.
Mike