Classic/Antique Car Repair: 1951 chevy pu, amp meter, correct voltage

Question
I have a 1951 chevy stock pu. Amp meter is discharging. when I increase the rpm's the meter moves up to the midrange or "0".
Will not show charging to the + side.
I have changed the generator, regulator and battery. They all should be in good working order but the problem still exist.
I have checked the wiring as best I can. I also polarize the new regulator exactly per the instructions that came with the new regulator. still got the issue. I believe the gauge is ok. Got any ideas what I should do next. I also have check the belt to make sure its tight.

thk
coy

Answer
Time to get a voltmeter across the battery. With the engine running at about 1500 RPM the voltmeter should read around 7.3 volts with all the accessories off. Then repeat with the lights on and the reading should be close. If the readings are lower then the generator is not putting out correct voltage or there is a lot of resistance in the system. If the readings are correct then you are right the gauge is wacky.
Brad