I am having a similiar issue with my 90 300SEL. I get a lot of rattling when I drive over gravel. Sounds just like a Mcpherson strut with a bad top bearing.
Can you tell me....what are guide rod bushings?

Thanks

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1995 E300 Diesel
1994 E320
1999 C230K
1994 S500 W140
1990 300 SEL