That means the crank is dated to the 2nd week of '67 and yet the 39-52T chainrings it has appear to be '69-'71 vintage. I don't think this is a '69 bike so I believe a previous owner changed the chainrings at some point.
I forgot to ask about the 2 symbols on either side of the SCHWINN stamp on the bottom bracket cones. Those were a form of date code around that time as Schwinn changed them every year up through '72 (they were discontinued after that). For example if the BB dates from '67 it should have 2 triangle symbols on either side of the SCHWINN stamp.
I don't believe that derailleur is original, especially not with the riveted badge and metal pulleys. A '68 or later *should* have come with a "Schwinn Approved" derailleur using smooth plastic rimmed pulleys. Since it is older than the rest of the bike it may have been a replacement purchased from dealer stock. Another clue is that it appears to be in such good condition. Note that those early Sprint derailleurs go for quite a bit on eBay!
The freewheel should also have a letter code, which I believe is a date code. I have a '69 Varsity with that same freewheel and an "L" code (the front hub on that bike is also "L"). Unfortunately I don't know how to decipher those codes (yet), although so far I think the letters may be month codes for '68 production. The Schwinn Approved hubs replaced Sprint branded hubs (they were the same except for the branding) in early '68 from what I have seen. I believe the same is true for the freewheels.
