I would suspect the battery. The 6v batteries can sit around too long and sulfate if it is a lead acid battery. How did you test it? Next I would make sure your connections at the cables are clean and tight.

Dave

I tested the battery with a volt meter and it says 6v. Also I tested that the negative cable is grounded. I found 1 fuse under the dash and the continuity was good

6.0 volts? A fully charged 6v should be about 6.3 to 6.4. Would the car crank with the old battery?

No, the gauges don’t register either with the key on

@buckaroo01-2-2-2-2 Power to the ignition switch usually goes via a heavy wire with a ring terminal, which shares the stud on the starter switch with the positive battery cable. The engine should crank over with or without the ignition switch being turned on. Does your battery ground cable go to the frame or to a bolt on the engine /transmission?

The ground goes to the frame. The engine does not crank with the starter switch.

Check your battery voltage when you engage the starter, if it drops way off it would be the battery. The wire coming off the starter post goes to the amp gauge, have you checked for voltage there? 

Is it possible you did not remove the insulated protective cap on the battery when installing the positive cable. Check for voltage at the positive battery cable end at the starter. Either a bad cable or poor connection if no voltage. Do you have working  headlights? When you do find and fix the issue be sure to charge the battery . 

I tried the headlights and they do not work. The starter won’t crank at all.  This new battery has a voltage of 6.43.  The entire electrical system is dead.  Any ideas.

"Check for voltage at the positive battery cable end at the starter." 

I checked the voltage at the positive battery cable end at the starter and the voltage is 6.45

Did everything work OK before you changed the battery or has the car not run for a long time. I believe there should be a heavy wire connected to the same stud on the solenoid and it would go to the ammeter. From the ammeter next to the ignition switch. Check for voltage at each point in line.

The car stalled in my driveway after driving. I was unable to start the car and the battery ran down where it wouldn’t crank over. I replaced the battery and now I don’t have anything electrical working. The gauges, headlights, and everything else does not work. Wher should I start checking things out?

Electrical gremlins can be difficult. Unfortunately there's often no easy answer. The only sure method I'm aware of is to check one connection at a time, start where you have power (battery to starter), then test the next connection in line. If you have continuity there, test the next in line. It sucks but it's the only way to do it that I know of. You say you checked the main fuse. How did you check it? I've had them blow and not look bad with a cursory inspection. If you've not tried a new fuse, that would be my first step. Good luck.