1955 series 1 Chevy pickup voltage

Recently found a series 1 1955 Chevy pickup. I read competing voltage ratings for 55 trucks. Some sites say the 55 series 1 is 6 volts others say ALL 55 GMs vehicles were 12 volt. Which is it. The truck had been in a barn since 84 no battery was in when I found it.

 

Normally the larger terminal would be positive. If it goes to a ground the vehicle would be six volts.
I have no idea why I know this. I am so oldI forgot where I learned this. Good Luck

 

^^^
Not so ....
Size of battery post has nothing to do with + or - ground.
First series '55 Chev is still 6v & is negative grd ....
There hasn't been a positive ground Chevrolet since the 1920s.

 

1st series were 6 volts. An ez check if it’s a complete truck is a 6 Volt has a NO ballast resistor in the wiring to the ignition. The 2nd series is definitely a 12 volt with a ballast resistor… One other check is the battery in under the p***enger floorboard on a 1st series.

 

yeah but the positive terminal on the battery is always bigger

 

The original 6V cables would be about twice the diameter of 12V cables if they were still original.