The suspension on the W123 and the W126 are almost identical except for the brake mount support, also called the guide rod mount. The W126 has a different unit. Otherwise everything else is the same.
As posted check the ball joints. and possibly the shock absorbers may be going internally.
Use a pry bar and see if any of the suspension bolts are not fully torqued.
Also don't forget the sway bar mounts

http://207.210.95.34/~boostd/

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car