The ZF has lifetime oil according to all the car brands that use this box. However ZF themselves recommend to change it at about 100.000 km. To change out all the fluid, you have to go to a specialist that can flush the entire box. I had mine done at 145.000km by ZF and they also changed some rubbers and a connector, but they assured me it is now good for at least another 100k.
For the dif, I change it every 2 years (engine oil every year), it’s easy and cheap.