Genuine BMW M Performance Limited Slip Differential. Fit F20, F21, F22, F23 M135i M140i M235i M240i. Your chassis number can be found on your V5/registration document next to VIN/Chassis/Frame No. And it will start with WBA, WBS, WAP, WBY or WMW. It can also be found in the bottom corner of your windscreen on the passenger side (looking from the outside of the vehicle). Please Check out our other items in our shop. If you would like something changed with your order or would like your item sent 1. Class instead of 2. If your request is urgent, please call the parts department at Ocean Torbay. Please bring a form of ID if you are collecting. Our collection & return address is.