is it because the ride isn't smooth anymore? loud bumps when going over bumps? I know some other ml'ers who changed there shocks at 80K miles as well.. could you have gotten aftermarket shocks? Sorry I've never done a ML but I've done suspension work on subaru's and hondas and they are so easy... I'm sure its similar.. just be careful when you take out the spring! btw: takes some pics of the install =) I wanna learn too haha..
hope these pics help you out!