Normal people would not be able to do it themselves because of the variety of end plugs/connections required.
They are unlikely to be able to dismantle the complicated connections/plugs without breaking them. They then have to source new ones from Merc (even if they sell ALL the different end plugs seperately) or try and get them elswhere.
Have you seen the engine ECU plug alone with some 50 pins in it !!!!!!!!!!!!!
The actual replacement of the loom is the easy bit, but if you have never done it before then allow a day for that I would say.
All references to above are to the all electronic HFM engined 124 (6 cylinder).
