The outer washer became obsolete with the W210, the new style nut has a machined face which rests on the bearing itself. Make sure its facing inwards. Its also wise to fill it to the oldschool Mercedes spec (lots of grease in the hub - approximately 70 grams) - and its also a good idea to use a modern grease like a full synthetic lithium complex or a polyurea base if you live in an area with cold climate.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)