ahhhemmm! Back to the serious topic of this thread (boring little F**t, eh?)....
Have to agree with Keef about the HU's location being somewhere other than Oz. While I don't discount that the vehicle may be in use somewhere with the RAAF (though I can't read the letters on the door...), the following points might be considered in arriving at a common understanding about the 'who what which where' of this image:
(1) there are no HUWs, HUPS, HUAs or any form of HU on the RAAF's vehicle register. (At least none that I've found, anyway, and I have a pretty good handle on such things, I think)
(2) the RAAF were assigned vehicles from other sources while overseas that didn't make the register (those few that came back to Oz with RAAF units did), and sported 'RAAF' on the doors to identify them while in temporary RAAF service. This may be the case here.
(3) The tree doesn't look like a Eucy to me.
(4) there is only one headlamp: Aust CMPs were all equipped with two Head lamps in Oz: those that arrived with one, were retrofitted as a service requirement.
Leads me to conclude that whoever the hoon is that's in charge of this 'Ute', he ain't Downunder (unless you mean down under the truck trying to fix the wretched thing ... it is a Chev after all.)
Mike C