Also, in the U.S. we can access for free the Mercedes Benz parts data base "EPC On-line". As part of that powerful tool you can find what part is used in what series of cars.
https://epc.startekinfo.com/epc/welcome.jspThe data base includes all "post war" cars including the 170/220 models. It includes pictures of the parts page with part numbers and replacement part numbers. The data base has other search functions that are helpful, such as entering a part number to find what car it belongs to.
To subscribe, you have to enter a credit card for identity and citizenship verification, but you are not charged for the basic free service. Thank you MBUSA!
To answer Charles' question, I used the EPC on-line to determine that the Ponton W120 does not share any parts with the 220 W187 differential except for one adjustment screw.
This hypoid differential was designed for the 300 (W186) and was shared by the 170Vb (W136), 170Sb (W191), and the 220 (W187). The actual rear axles and axle tubes are specific to each of the above models except for the 170S and 220 which are the same.
