Originally Posted by
tdracer
Are you sure, I didn't think they built -100s with the ten upper deck windows per side.
Early B741s/B742s were built with 3 windows, later ones with 10.
In addition, some airlines (including BA in the late 1970s) modified their early aircraft, which involved replacing the skin panels as can be seen on this NW B741:
https://www.airliners.net/photo/Nort...ng-747-151/635