2 exchange-standard references match the MERCEDES S-Class (W220) 320 CDI 197 hp (145 kW diesel). Output is the deciding criterion: a part meant for another output of the same displacement will not fit.
On the MERCEDES S-Class (W220) 320 CDI 197 hp, the code stamped on the part remains the safest matching criterion.
Other engines of the MERCEDES S-Class (W220): S 63 571 hp, S 63 544 hp, 500 435 hp. If the code stamped on your part is legible, search by reference remains the safest route. 24-month warranty.