For safety reasons if your Ford Gas Tank is in need of repairs, it is best if it is replaced and not repaired. The reason a gas tank might be in need of repairs on your Ford is because it will become rusted in time from being exposed to road salts and other environmental conditions that components on the undercarriage of a vehicle have to withstand.
To help the gas tanks that are produced by Ford last as long as possible they are constructed of galvanized steel. This provides protection against the elements for many decades under normal conditions. When rust does appear on the exterior of the gas tank it is only a matter of time before the fuel will seep out and cause the owner of the vehicle a problem.
Some Ford owners have been known to apply an epoxy to fill in the hole. If the rust is on the seam of the tank, the epoxy has also been placed there. The end result of just of sealing the gas tank is only temporary before the leak appears again.
Other owners have investigates the welding up of the rusted hole or seams at a machine shop. Most shops will not do this type of repair since the vapors of the gas are highly explosive. This process can be done, but the cost of preparing the Ford gas tank for the heat of a welding torch is generally near the same as a new component.
For the above stated reasons and to help keep the occupants of the vehicle safe, if you have a fuel leak in your gas tank, replace it with a new one. It is faster, safer and cheaper with more permanent results than the alternatives.