Classic/Antique Car Repair: 1950 Chevy pickup truck, chevy pickup truck, delco remy

Question
Hi, I have just bought a 1950 Chevy pick up as a restoration project. I am have not been able to find out if it has a 6 volt or 12 volt electrical system or if it is positive or negative earth. After checking around it, the only clue that I have found is that one of the headlight sealed beams shows 12v on it.Can you give me any guidance? It does have black battery cable to the body earth and red to the starter solenoid which makes me think it is negative earth. Thanks Neil.  

Answer
When that truck rolled off Chevrolet's assembly line it was a 6 volt system NEG ground. But that does not mean that in the intervening 60 years that some one has not changed it over or attempted to change it to 12 volts. My next step would be to clean the starter and the generator off looking for a tag or a number stamped into the frame. This should also list the voltage. The voltage regulator should also have the voltage and polarity stamped in the base near one of the mounting screws if it is a Delco Remy original type equipment.
Good Luck, Brad