OK here's where I am. I put in a new cable and that stopped the bouncing back and forth between 15 and 35. The needle still vibrated a little and the speed is is definitely wrong. Today I put in a new speedometer. It still doesn't budge until speed is about 20-25 but the needle operates smoothly and stays stable. Sure looking like a mixed ratio problem. I can pull the small gear and count the teeth. I'll also check the rear end to confirm ration. Can someone tell me where to look on the transmission for a model number. I'll see if I can get pictures. I'm assuming the instrument cluster is correct for a '56. It has 4 guages rather than the 2 that the 55 has? Or does it have 4 because it's a truck? Yes, I do have maintenance manuals on the way. I really appreciate all the help.
