Perhaps when the noise from the other items was taken away you could hear it better ?
Are you SURE it is the pinion BEARING... as compared to the pinion and gears in the differential ?

It always worries me to see a thread with no reply hours after it hits the forum.

I got out my chassis manual on this.... and studied the crazy translations and pictures carefully.
Knowing that I am frugal may help with my crediblity on this one...

GO and get the differential from where ever you can find it... Well worth $200 because even if you tear this thing apart and think you have fixed it you will be going and buying an intact one to replace it with SOON.

It is my considered opinion based on the number of special tools shown in the manual, and the type of bearing it is ( tapered roller ) ... which always require PRELOAD to last... and the fact that while you can replace the pinion seal you have to take the differential APART to press off and on that tapered roller bearing...

Unless you are a well equipted MB dealer with well trained mechanics you can't even redo that bearing out on a workbench... much less in the car...