You will not be able to put in the actual mileage. You can go to a dealership and show them the mileage, BEFORE, you switch out the instruments and they may set the new ones to the proper mielage. However, this is not much of a problem. You will be able to tell the correct mileage as you know the starting mileage. The only thing you need to check on is the laws in your state for selling a motor vehicle and stating its correct mielage. On the back of most titles, there is a place where you can state that the mielage on the odometer is not correct. JUst keep all your paperwork and the miealge at which you changed it so you can tell the buyer what the mieage is. If there is not a place to state incorrect milage on the back of your title, go to your local DMV and find out what the law is for selling a vehicle with incorrect odometer mieage.