Squeaking shocks / design problems?
 

I am going to replace the rear shocks of my 2000 ML 430. My concern is that the replacement shocks will eventually squeak. I have found Sachs, which the part guy told me are OEM's. Is the problem the design of the Sachs shock, or the design of the ML?

Both. The part that squeaks is the ball joint at the bottom of the shock. Rather than just using the typical hole with a gromet and bolt through it (which allows for 2d motion), MB decided, in its wisdom, that full range of motion joints were needed on the bottoms of the shocks, so they put ball joints on them. Eventually, the balls rust up, as even though there is a rubber boot, water gets in there, and then they squeak. There is no way to grease them to prevent the problem, as the boots are sealed and there is no grease fitting. Any shock that fits this application will eventually develop the problem.

Would it be at all possible to drill a small hole in the lower A-arm and install a Zerk fitting?

The squeak is not actaully from the A-arm, but from the ball on the shcok itself. Have a look at the thread on rear shock replacenment and look at the pictures posted there. Under the accordian rubber boot on the shock is the noisy culprit. I guess you could cut the boot open and try and lube it, but opening the boot just invites crud in there to amplify the problem.

Sachs isn't the OE shock on the W163 chassis. Shocks are USA OR Canada(No. America) made by the Arvin company!