[Tyler1970FB]

I have a 1970 Fastback and the speedomoter is not functioning right. Most of the time the speed is approximately 10 mph over actual speed. How do I adjust the speedomoter to accurately reflect the true speed?

[dollarbill]

Maybe in the past somebody changeed the rear end gears to a higher ratio. Or there is a different diameter tire being used ( a smaller one). You should be able to get a different speedometer gear to correct the difference. Usually at the end of the speedo cable going into the side of the trans. Good luck!

[Cracker289]

I am pretty sure that Mustangs Unlimited has every speedometer gear available for every transmission and every rear end gear that there is out there. But I don't think it's in their 64-73 catalog, I think it's in their 79-03 catalog.

As long as you know your rear end ratio and what transmission you have, they can help.

[Max Power]

National Parts Depot not only has all the gears, they have pictures showing the different types and a handy conversion chart for people who have changed gears.