Hi John,
55 on red is an infantry Unit Sign.
1973 production/delivery so not a SVN-deployed vehicle (the bulk of Australian forces had left SVN by early 1972) .
25-209 was sold out of service prior to 1993. This is a post-1972 registration, so details are not held by the AWM. (AWM126 registration books end when the registration system was revised in 1972).
Nice truck.
Mike
