Nice vest in great shape! However, it's not SADF. That is a South West African Territorial Force (SWATF) Pattern 83 vest. This particular one is a first pattern type. Later versions deleted the pen flare pocket on the shoulder, and had the rear pack sewn to the vest. On a side note, the removeable pack was also designed to attach to the back of the SWATF rucksack. So, you could take the pack off the vest, put it on your rucksack, and then use the rucksack and vest together.
These vests were made by the South African firm Three Spears on behalf of the SWATF. Many found use with SADF troops operating on the Border, and they saw extensive use with 32 Bn. Once in a while you'll find a photo of one of these still in use with SADF reserve troops, but that's rare, as the SADF Pat 83 holds a lot more kit.
As you've noted, the DPM fabric used on the shoulder pads and map pockets is the same type as used on early 32 Bn and Recce kit.