It may have deployed to Namibia as part of Australia's contribution to UNTAG.
This operation was a on again / off again thing for over 10 years from 1978, with the deployment finally occuring in 1989. During this period, the Australian Army had quite a few vehicles prepared in UN white and placed in storage at Moorebank. This included S2A's, one of which was a Workshop that is currently on display at the AWM and an Ambulance which is on display at Bandiana.
The initial deployment to UNTAG included 24 Land Rovers, 19 Unimogs, 26 heavy trucks, 43 trailers, 8 bulldozers and a variety of other road-building equipment such as graders, scrapers and rollers.
Very good find 👍