Sure a headgasket can blow on any car. They don't blow up in your face, they usualy give you lots of warning.
AFAIK the M103 had a lot more trouble with head gaskets then late production M104's ever did.
At 200k miles some parts in the front suspension of your average W126 like the ball joints, guide rodes, and shocks are in need of replacement.
If you want to talk front suspension W140's have those fluid filled lower bushings that always seem to leak.