Originally Posted by
motogeek
rhm, the serial number on this bike is, in fact, 5 digits, but they begin with "99...", so they aren't far from being 6 digits. The current owner seemed to think it was a `1959 or thereabouts.
Yeah, I understand that; what the previous owner says is not to be taken lightly.
On the other hand, if we accept the dating of the the two serial numbers presented so far, that is rustystrings61's serial number 241247 = 1974, and mine 165167 = 1959, and assume the yearly output between those dates was approximately steady, then that's about 5000 bikes per year. If we assume yearly output was similar in the years before that, then this pushes your serial number back to 1945 or so.
Obviously that's a very rough way of coming up with a very approximate guess at the date. We need more data, and I'm sure it's available.