[TBONE1964]

Has it always been this way? Have you changed your tire size lately? Have you changed the rear end (axle) or the transmission lately?

The cable will not cause this. Is the speedometer needle bouncing when you drive it or is it smooth?

If you have a local transmission shop, they can calculate your gear ratio and tire size and put the matching speedometer gears in your trans. That will make it read correctly. Any time you change gear ratio or tire size, it will make the speedometer read fast or slow depending on what change you made.