It amazes me that you would have this problem. I have never seen a MB differential have the bearings fail without lack of lubrication or improper repairs. Pinion seal repairs often cause the bearings to fail. This occurs because the pinion set up is disturbed by overtightening the flange nut.
Bearing replace is not a drop in procedure. The whole thing has to be re-set-up every time new bearings are installed. Very unlikely that the same shims would work, especially on a unit that failed so early.
Personally I would install a used unit or a MB rebuilt. This is not DIYer stuff. Very few technicians know how to set-up differentials. If you don't make the measurements you are guaranteed to fail with this.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician