They are normally mounted on the lower part of the dash just to the right of the column. Most cables are from 48 to 60 inches long but can be tailored to fit your application. The Truck Shop in Orange, CA has reproduction Ford cables for about $50. Other aftermarket sources that sell Ford parts may have them also. If you don't need one with "overdrive" stamped on it, you can pick up a "T" handle cable at most auto parts stores.
Fred