See also:

Removing the ball coupling
Observe the manufacturer's installation instructions. Press the protective cap into the ball coupling recess. Make sure that the protective cap is firmly in place. ...

Vehicle data, GL 450
The data stated here refers specifically to a vehicle with standard equipment. Consult an authorized Mercedes-Benz Center for the data for all vehicle variants and trim levels. ...

Important safety notes
WARNING To help avoid personal injury during a collision or sudden maneuver, exercise care when storing objects in the vehicle. Put luggage or cargo in the trunk if possible. Do not pile lug ...