My 94 E320 has one fuel filter. It is located near the rear on the passenger side under a cover. Remove the screws securing this cover and expose the filter and fuel pump. Use a clamp on the hose between the pump and the filter to prevent fuel spillage; remove the fittings on the inlet and outlet sides of the filter; remove and replace the filter; use new copper washers at the connections. Start the car and check for leaks. Reinstall the cover. Pretty easy. No smoking while doing this!
regards,
Mark