[speeder]

Yep, make sure that it's not tires before going any further. A bad tire, (that looks perfect to the naked eye), can cause a car to pull or drift in one direction.

On that car, and all other Mercedes-Benz cars of the era, there is a plug on the bottom of the steering box which you can remove and find the center of the gear, where the car should be aligned. There is a special tool, really just a threaded plug, for holding it in that exact place while being worked on but you can also just observe the divot(?) in the shaft through that hole with a good flashlight and know when it is centered.

The steering gear box will not leak when you remove that plug if it is centered. Once you find that spot on the gear, make sure that your steering wheel is pointing dead straight or correct it at this time. This will of course not change your alignment settings but the car MUST be aligned with the wheel centered in this position. The steering gear box has a "self-centering" feature engineered into it as well as the turning circle in each direction will be effected if this is wrong. You cannot bypass this step, it is not optional on a MB car.

Start there and switch tires around if needed plus have a good shop take a second look at all suspension components. No one competent will align a car with worn parts...it just isn't possible. The gear being centered and the wheel being installed on the correct spline are crucial, for several reasons.