When putting a 12v to 6v reducer on a gas gauge for a 50 Chevy, where does the reducer goes? In line with the power coming from the fuse box, or in line from the gas tank sending unit?
Right now I have it done with the power wire from the fuse box and it doesn't work. Thanks.

As I understand it, the "sending" unit in the tank is a variable resister that goes to ground and does not actually send anything and the power reducer should be on the power line to the gauge.

Install it in the line from fuse/ignition to gauge then ground the termimal going to the tank, check gauge reading. Next remove ground (and wire to tank) then check gauge. One way should read full the other empty if no change you have a defective gauge. If gauge has been hooked to 12 volts it is probably shot.
Good Luck.

Thank you Bill, I'll try that tomorrow.

Okay, I got the gas gauge hooked up with the 6v reducer and it works when the ignition is on. The only problem is that the needle seems to read full at all times. When I turn off the car then the needle goes back down to empty. Do I have a defective needle? Thanks.

Is your iank full? You could have a grounded place in your wiring, you could have a defective sending unit in your tank, the tank might not be grounded, or you could have a bad gauge. go to tank and unhook the gauge wire. While someone watches the gauge with the key on, ground the wire if gauge reads opposite when you ground wire then your wiring and gauge are ok. Then you either have a bad ground on your tank or your sending unit is bad. You could start at gauge and unhook the wire from the sending unit then jump that gauge terminal to ground. If you see the gauge reads opposite then check as above.

I will check, thanks. I will get back to you.

Having done several 6 to 12 conversions, one thing I learned early is to not use a "resistor" style voltage reducer. They are nothing but junk and unless you perfectly match them to the load, you may get any thing for voltage. To do the job right, take a look at the solid state voltage reducers sold by Ron Francis Wire Works. He sells two versions...one small one that is just perfect for things like gauges. There is a large one with 15 amps capacity that can be used to power a heater fan or old style radio if needed. Being solid state units, they put out exactly 6 volts regardless of the load. (up to the rating of the unit, of course)