It is definitely a Deutz engine.
Atlantis Diesel Engines (ADE) built a wide range of Deutz engines under licence.
They started out by making engines for the Samil range of trucks, which in turn are licence built Magirus-Deutz models.
Their range of engines was expanded to provide for other SADF equipment.
They also added engines and other parts for Deutz-Fahr agricultural machinery (tractors, harvesters, etc.) to their product range. Also Perkins, Mercedes and other engines for the truck manufacturing industry.
When the New SA happened, sanctions, military contracts and subsidies all evaporated and ADE closed down.
This article about ADE's demise dates from 2001
http://www.fleetwatch.co.za/magazines/oct01/20-AnotherCasualty.htm