Q: My new gas gauge should read from about 10 o'clock for empty and about 2 o'clock for full. My needle goes to about 5 o'clock.

I have a 54 Chevy 3100 P/U. The original gas gauge was not working. I suspect the previous owner burned it up when they converted to 12v. I can put a volt meter on the lead wire and it reads 12v to ground. I purchased a new 12v gauge. When I installed it, the needle on the gauge swings past full and buries the needs almost 180 degrees opposite the half tank mark. If referencing a clock, the gauge should read between about 10 o'clock for empty and about 2 o'clock for full. My needle goes to about 5 o'clock, way off the scale. Nothing changes when I disconnect the sending unit. The needle does swing back when I disconnect the lead to the gauge. Do I have a bad (new) gauge, do I have a bad (miss-matched sending unit, should be 0-30 ohms unit) or could I possibly have the two wires on the gauge reversed?

My car has 100000 miles.
My car has a manual transmission.