Csnow is right. That's why the industry has trended away from serviceable bearings to the throwaway units now manufactured for most vehicles. There were simply too many mechanics - truck and automotive - who could not properly set the preload on a bearing, which caused premature failure.
If it failed during warranty, it was a constant battle between the bearing manufacturer and auto manufacturer. The auto maufacturer would always say, "You build lousy bearings that can't last!". The bearing manufacturer would say, "Your mechanics at the dealership don't know how to properly install a bearing!" It keeps going back and forth like this and the evidence is lost.
I guess MB still trusts their dealership mechanics to service a bearing. At least the ones on my 95 E320 are still serviceable in the front. And yes, I used a dial gauge to set the preload last time I serviced them. The specs are so tight I couldn't do it by feel.
95 E320 Cabriolet, 131K