I apprenticed under the end of the '65, but the first NEC I owned was the '68, as I tested for my first journeyman's under the '68. Somehow that book got left behind.
Highlights of changes. . .
Romex was still available with tar (bituminous compounds) in the jacket and the ground wire was #16.
TW was the dominant conductor for raceways.
GFIs were not required.
Aluminum branch circuit wirng was not a problem.
Wirenuts could splice aluminum and copper conductors.
CO/ALR devices didn't exist.
Supplemental grounding at the service was not required (most commonly, the ground rod).
