This is in follow up to my earlier post about the nervous on-center
steering in my 1987 300E.

I took the car back to the tire store that did the last alignment.  The
initial reading before doing anything was that the left front toe was
too far out and the toe on both rear wheels was out of spec, with the
left being too far out and the right being too far in.  Also, the camber
on the right front wheel was out of spec.

So, the alignment tech did the alignment and got everything squared away
with a nice printout showing everything with green arrows as they like
to see.  Then...he says he pulled down on the front sway bar to compress
the front suspension and all the alignment readings changed.  The camber
changed on both front wheels and the right front toe started to move in.  
The readings stayed this way after he let go of the sway bar.  He said
he has not seen this before.

The tire store was very puzzled by this and directed me to take the car
to the dealer to have them figure out why it won't hold alignment or
tell me if there is some special trick or tool that is supposed to be
used when aligning the car.

Even with all that, the car seemed better on the drive back to work from
the tire store.  I am now wondering if there is some trick to aligning
the W124 chassis and if I should take it to the dealer to get this
sorted out.  I am also going to look at the front sway bar and bushings
as was suggested by someone in response to my earlier post.