Maybe he means the twelve pointed nut or possibly a spline nut?
Assuming the nut is the same as my w124 sedan, it's just a twelve pointed (double hex) nut. You can use a standard 12 pt socket.

http://www.samstagsales.com/mercedes.htm


Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E