Too old, try to get one with factory warranty....
If you own an allroad you know what you are in for. Mercedes suspension is far better and longer lasting (balljoints and control arms). Engine is easier to work on should something come up. I am 5 years into a 2008 R320, love it but problems are never easy you need factory software for true fixes not guesses. I have not heard of rust or salt issues with the 164, news to me they are made but could understand lines would be hard to replace. Mine is at the point of constant care- painting suspension and arms that are starting to rust, chasing rust that is starting to form (jacking points hold dirt and moisture), keeping on top of stuff is getting harder but I keep it very tidy and obsess over it, cannot afford to replace it! I got mine just out of warranty and full dealer history that was upto date, it took a long time to find a nice one that was going to be a good purchase