Hi my 2001 C320 is going in to get the rear differential worked on because of the recent humming coming from it,,,, My cars warranty runs out in about 500 miles. So this will be the last service under warranty... What else should i have the dealership perform in order to get the most from this last service? Will they only work on the car when theres something wrong with it? Or can i request to have other work done?

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0