Some of the weakest links in the chain of the w123 s overall construction that Ive found are as follows.heater controls,window switches ,glovebox door,vac system,hood latch ,hood cable, rust at hood arm area,rust at rear window area ,and yes ,Im going to say it ,the air cleaner bracket.These cars are lasting 2 to 3 the life life expectances over normal cars so the contest really is no matchup to any other car ,period ,but if you have fixed a part that will never fail again I would like to hear about it.I just bullit proofed my hood latch with a part that already is available and is still Mercedes, I did away with the plastic grab piece that hides away in the grill,its replacement is a bent piece of diesel fuel line that Ive shaped and curled as the pull knob and sleeves right through the latches assembly piece nicely.I would like to replace the glovebox piece with a door assembly and a block of varnished wood .Ive never seen a door pull / latch fail.A lockable piece and cup holder possabilities also.As far as the air cleaner bracket goes ,it gets shacken to death when the engine mounts are starting to go south,it will break at a certain area along the bracket if the mounts are not serviced.Another couple of rubber mounts and an improved bracket that allows for 2 more mounts should solve it.Any new additions are cures youve built into the car?