Rebuilding a MBZ differential is not a simply 'take it apart and put it back topgether'. Installing the ring and pinion gears in the proper positions in order to achieve a noise-free operaion is very problematic. I suggest you buy a good used one and spend the 2 weeks of effort and disapointment you saved on a well deserved vacation.

Not that it can't be done with the training, time, tools, and attention to all the details, but not a good way to spend limited time.