2 exchange-standard references match the MERCEDES M-Class (W164) 420 CDI 306 hp (225 kW diesel). Output is the deciding criterion: a part meant for another output of the same displacement will not fit.
On the MERCEDES M-Class (W164) 420 CDI 306 hp, the code stamped on the part remains the safest matching criterion.
Other engines of the MERCEDES M-Class (W164): 400 CDI 250 hp, 270 CDI 163 hp, 450 CDI 306 hp. If the code stamped on your part is legible, search by reference remains the safest route. 24-month warranty.