The W163 (ML's) have a 14MM wheel lug bolt that require 100ftlbs of torque. For safety I would have the hub replaced.
There isn't enough material for a heli-coil to work properly, however a Time-sert might hold. 14MM x 1.5 thread
A new hub lists for $50. you also will need a new front wheel bearing( $61.) as it will be damaged when the hub is removed.
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