Ford Mustang: speedometer, speedometer cable, vintage mustang

Question
I've tried to hook up my speedometer cable to the transmission, but the speedometer won't work.  I checked the cable and gauge and they both work, is there something missing in the transmission itself?

Answer
In a vintage mustang transmission there`s a gear that the speedometer cable would attach to. It has splines or can be called a spider gear. Possibly yours is missing or lost in the transmission. If it is there, it could be stripped out or inoperable in some way.