There are instructions in Bentley's for changing both the "standard" coding plug and the "updated cluster" coding plug... the only thing mentioned is the little sticker for the door that you record the previous mileage on. Of course, my odometer has hit an inaccurate 300,000 so that raises a question? Anyway, would like to make this a simple swap, but don't know if the actual speedometer has the right gearing (or electrical set up) to give me an accurate MPH reading... I also use the "distance" and "limit' on my OBC and don't want to lose the fuctions...not to mention a speedometer which is off.