It's a straight swap. You don't need to correct the new speedo unless you take off the needle to correct the mileage. If you swap the whole cluster (including the tach and other guages) it'll work even if your old cluster didn't come with a tach. This is because the tach gets it's info from the wiring harness that the cluster gets plugged into. I'm guessing a normal Taurus can hit somewhere around 105-120 MPH.