As far as I know, my aus delivered sprinter was fitted with P/S before it had a 4AGE installed, the P/S and the aircon was removed to make the conversion easier.
This is what the previous owner said, could be BS, but I did get all the P/S related parts along with a shit load of other spares when I bought the car.
So if anybody in SA wants the P/S steering arms, pump etc, im open to offers!
Personally, I love no P/S on the sprinter, my last 3 cars had power steer and I hated it (except in carparks!)