I thought only in 1962 did the top tubes flow down and are the same tubes as the dropout tube? I stick with 62 LOL! I dont think a serial # could help ID any further?? Just the date it was made. I like those frames.
1960 has the two straight bars 'detatched' from the rear seat stays; 1961 they are continuous from the seat stays. I own several of these bikes in both styles.
Post the serial # & I'll tell you the day it was made.
The 26" 'double straights' were mostly Typhoons.
I also saw a Schwinn 'Skipper' today that was just like that...