Generators ????

[JonC]

I picked up a 48 motor I am using in the 40 P/U. When I did the guy I bought it from made a statement that he thought the generator was converted to 12 Volt. He never ran the motor because he wa building a street rod and using a 350. Is there a way to tell if in fact it is 12 vs 6 volt? It is a two brush with the typical two posts. I have read that field coils could be switched to convert these but I have zero experiance with this issue. Any suggestions?