For many reasons, the timing chains really never need replacement on the six cylinder engines.

It wouldn't hurt to check for timing chain stretch and to replace the chain tensioner.

As far as engine lasting, it seems that the valve seals and valve guides should be replaced every 250,000 miles or so. The bottom end of these engines allegedly never wear out.

As far as maintenance, I always tell people to not forgot two items, which are a critical part of your car's maintenance, but often get overlooked because they are the only maintenance items performed in time, not miles:

1. Brake Fluid - required replacement interval - every two years.
2. Radiator Coolant - Required replacement interval - every three years.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".