On my 1994 w124 E320 I have owned it for nearly a year now and put about 10k miles on it (it has 127k now). The car was in good condition when I bought it, however it came with no service records/history (probably a mistake...I know). I completed the 120K service as suggested by the owners manual (plugs, fuel filter, all fluids changed including the differential, air filter, cabin filter, etc.)Anyway, I would like to keep the car in as good of shape as possible (without breaking the bank obviously) and would like some advice/information about the suspension, differential and tranmission.

First, where can I find some good information about the suspension setup, names of parts, their purpose, etc. I know quite a bit about cars in general, but suspension is definitely my weakest subject.

Second, assuming the suspension components are all original what should I be looking to check and/or replace (and how do I check each component). I found the 4 P's as suggested by LarryBible, and have no problem jacking the car up and push/pull/pry/prod on the components, but I have no clue what to look for.

Third, the transmission makes a slight cluck (i think in the rear-end) on the 3-4 shift once in awhile. It seems to be only under light-moderate acceleration and after doing some research I would guess that it is the rear differential mounts or flex disk.

I am hoping to complete much of the service required on my own, once the weather warms up a bit here in the tundra region.

One further question - at idle i can feel a slight vibration of the engine, can I safely assume that the engine mounts are tired after 12 years and 125k+ miles.

Thanks for the suggestions and help!

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE