to the FSM Forums Dark, and as Mike has said go to the Aussie Modellers thread in the General Discussion folder and say Hi.
Basically during WW2 the Aussies used the same marking as the British which consisted of a series of shapes to identify Squadrons and the troops that made them up, a diamond for HQ Squadron, a triangle for A Squadron, a square for B Squadron and a circle for C Squadron, the troop number was placed inside the shape. For more info, and seeing that you are based in Adeliade try contacting the Military Vehicle Museum at Port Adeliade, their Phone No is 8341 3011 try to ring them 10am and 4.30 pm on Sundays. Their website address is
http://www.military-vehicle-museum.org.au