I believe the original source for the Schwinn serial number information listed in the OP is here:
Schwinn Date Codes
From there it links to these pages:
i.d. FACTS
1948 through 1952
1952 through 1969
1970 through 1982
Note on the original pages where it states "Copy and print this info at will, it`s FREE.
BUT If You Steal The HTML And Post It On A Web Page In ANY Format, It Is Illegal"
In that case it appears that the info in the OP's links was reposted without authorization or credit.
I would only trust the information from the original source, as copies (especially unauthorized ones) can introduce errors. For example the
ORIGINAL 1970 through 1982 page it states: "NUMBERS ARE NOW LOCATED ON THE LOWER LEFT OF THE HEADTUBE (By The
Schwinn Badge On The
Front OF The Frame)", whereas on the
COPIED 1970 through 1982 page it states "Serial #'s are now on the lower left of the headtube, by the
Schinn badge on
fromt of the frame".