I'm researching vintage Rickenbacker basses for a possible purchase. In looking up the serial #s, it appears that the number one sometimes looks like a "1" and sometimes it looks a capital letter I. And sometimes it actually is a capital letter I. From what I have seen, it looks like at some point they started using a straight vertical line for both the #1 and the capital letter i, whereas on earlier basses the one clearly looked like a one. Can anyone confirm this and if so is there a particular year when they stopped differentiating between the two? Any info would be greatly appreciated.