I think that the only windowless 767 were the KC 767 mid air refuelers built by Boeing. If I remember right they were didn't start flying until 2003 or after, which proves that it was time travelling lizard men that attacked the world trade center.
I guess it could be the 767 300f cargo, but that would probably mean that UPS attacked the World Trade Center
Plus if I recall, there were wreckage pictures from the World Trade Center attack that showed part of the fusalage that had windows.
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My name is Ozymandias, King of Kings;