Classic/Antique Car Repair: 1966 Mustang Fuel Gauge, fuel guage, fuel gauge

Question
The fuel guage on my mustang does not work, it is normally at empty(left) but when I turn the key it moves about a half an inch to the right.  I am not sure if the issue is in the wiring or the sending unit.  Any suggestions on how to verify which is the issue and the what to do to correct?

Answer
If you can get at the wire to the sending unit, remove it and ground it. Then turn on the key. If the gauge moves to the full mark with the wire grounded then the problem is either a defect in the sender of a bad ground to the fuel tank. If the gauge does not move then the problem is wiring or the dash unit.
Brad