Quick Electrical Advise Needed

I'm fairly decent at some things, but electrical is not one of them so I need some quick advise. I just got a 1949 Cadillac Sedanette. How do I figure out if it has a six volt system or a twelve volt? The battery was missing when I got it, and there has definately been some modifications to the wiring. Trouble is that I don't have enough sense to make heads or tails out of it. Thanks in advance for your help.

 

Can you not just pull a bulb or two? They will say if they're 6 volt or not

 

Didn't think of that. Thanks for the help.