Two Unimog 'Mothers' were built and operated by SASR. The better example resides at the SASR Museum, and the other, very poor and stripped example, resides at the AWM. Not sure they are 'armoured', just very heavily modified. Pity its out in the weather.
The original concept was first trialed on K89, and was considered very successful, hence their continuation in service until only the last few years.
Mike C