Check out 'Common Problem' threads (sticky) in W210 forums at benzworld and MBworld sites.

Issues to be sure to check are 1) spring perches (especially from areas using salt on the roads), 2) rust (bottom of doors and tailgate handle), and 3) cats (check for rattle),

At that mileage check for service on transmission, spark plugs, and O2 sensors.

As always Inspect, Inspect, Inspect. No service history written records = keep looking. It is a common model and lots to choose from.

Finally, 4Matic gets a little poorer gas mileage and has a little more potential maintenance and repair. Generally, $500 to $1000 more in asking price. If you need it fine.

Good luck.