I plan on buying a W140 in the near future, preferably an S500/500SEL, and I was just wondering what some of their common problems are?

I already know about the wiring harness, and evaporator problems...is there anything else I should look for in a good W140?

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles