[Gearhead999]

If there isn't a cable in the car, yes you'll have to purchase a new complete cable.
Question....if there isn't a cable in the car, what is plugged into the transmission to keep it from leaking??

Anyway, get a new cable route it from the speedo head to the transmission and you should be OK.

To find the routing of the cable either find a car similar or check the Ford shop manual.