Do you have a pto system which needs parts/servicing, or are you looking for a pto system?
If you're looking for a pto system, it's quite a difficult thing to find locally. Several years ago I was looking for a full pto setup for my 416 to enable me to fit a Werner winch. I eventually imported a used pto box from Atkinson Vos in the UK. It then took me 18 months of searching to find the spline box and pto shaft locally.
Local places you could try:
Mogdoc - Ferdi might have something lying around.
C&D Unimogs in Sabie - it's been many years since I last visited them, but they used to have two containers full of mog goodies
Pon Steyn in the Cape - I've never dealt with them, but have seen them advertise pto boxes in the past
If you don't come right locally Atkinson Vos would be a good port of call. Friendly and easy to work with. Only problem will be the exchange rate and shipping charges....