Speedometer not working on 64 Barracuda.

I haven't fooled with early As but I don't understand how the hole that the center (spinning part) of the cable fits into can be round. The cable would just spin in it - that's why the cable is square. On a later A body (mine are 1970) you can't pull the cable out through the transmission end. There is a crimped collar on the cable, so it has to come out the speedo end of the cable, but maybe early models are different.