Speedometer not working on 64 Barracuda.

It has been so long since I had an early A that I don't remember if the speedometer end is square or if it has a nub on one side of the cable. Is your cable end square? Can you see anything inside where the cable goes (almost looks like a slot on one side in your pic)? If the car is running, jack up the rear (with stands, of course), start the car and put it into gear. Watch the end of the cable and make sure it spins. You can also pinch the cable end between your fingers to see if it stops. My Dad taught me that trick many years ago on my first Valiant. Cable had broken but had one wire still intact and would turn the cable just enough that you thought it was OK. Holding it would stop it turning. This will tell you if the problem is in the speedo drive/cable or in the speedo itself. .