I think.... Antenna head for a Vietnam era Radio Relay assembly. The radio (microwave) kit was usualy (but not always) mounted on international trucks. Later versions were mounted on Unimog Cargo w/winch.
The current Parakeet system does have an equivelant, which is mounted on the Perentie 6x6 Crew Cab.
There is a painting depicting Royal Australian Corps of Signals involvment in the Vietnam War which shows the antenna in use.
Pete
