Hay 01stang, Just Get A Speedo "whole Dash Cluster" From A V-8, Mileage May Be Incorect Like Smurf Said.....the Only Reason For It To Read Incorrectly Is If U Change The Gear Ratio In The Rear End....easy Fix, Change Speed Sensor In The Trans For One That Matches Your Gear Ratio...any Stang V-8 (close To Year Of Your Car) Speed Sensor Is Fine, As Long As You Dont Go Past 4:10....anything Past That And U Will Have To Call A Tranny Shop To Get The Right Sensor, Or Do Wut Smurf Said......they Way I Am Tell'n U Is The Cheapest. If U Change The Rear Gear U Can Get The Speed Sensor From A Junk Yard......easy Swap..it's Held On By One Bolt On Tranny Case....i Went From 85 To 160, It Also Helps When Your Best Friend Rebuilds Transmissions For Police Cars And Taxi Cabs,,, I Got A Badd Ass Aod!!!!