I'll throw in my story since my Shelby has Autometer gauges...
When I first got the car, after a few hundred miles, the speedo started bouncing and quite after about 20 more miles. The cable tied itself like a pretzel.
So I got a new one, lubed it up all nice and it happened again.
Found out I had the wrong gear the whole time (at the tranny)! It had the right amount of teeth but it was reversed from what the Tremec wanted. Might want to double check that
