The wiring harness that mercedes used to put under the hood of their MBs during the early 90s suffer a lot from hardened insulation and connectors. These hardened parts crack as soon as you touch them and therefore some of these engine wire harnesses are changed under warranty...
I renewed some parts of the engine wire harness in my 1990 300SL-24 as well. A lot of broken connectors and cracked insulation parts...
with a minor 600+k