For those of you running mechanical speedometers and can't get an accurate reading with gears and tires, go to an electrical speedometer. I recently installed the Auto-meter 160 MPH electric speedometer, installation and calibration was a snap. Readings are dead on with GPS check. I had T-5 and 3.73 gears and no combination brought me close with the mechanical guage. By the way old gauge showing 1921 miles, and 50" steel braided cable for sale.