The speedometer in my 47 Dodge jumps around and even shows an increase in speed as I am slowing down. It also pegs out on the high speed side while at highway speeds. The cable and speedometer are original. I just installed a new center disk and lightly cleaned and lubed the speedometer. Everything seems free. The cable is in good shape. I pulled out the inner cable and lubed up with the correct lube. I tried another speedometer and it did the same thing. The 727 tranny has a 30 tooth gear and looks in good shape. So the question is, does anyone know if I can use a 47 speedometer with my 727 tranny and 8.75 rear end?