speedometer problem.

[Rengo]

When I bought my car, a 1975 Duster, the speedometer read, 100mph in park, shut off and has been there for a few years. Is there any way to fix this?
I am eventually going to a tach. From fast lane west..

 

[faster4231]

Speedo cable attached to tach, unscrew it, the other end is attached to the back of your trans, if you remove the cable, its a $10 fix or just WD-40 it and replace it, should work, if it doesnt then its the tach itself. I have a 75 and had to do this to it