Now look at these pictures:
Photo © Gerard Helmer
In 1982, the plane has the full 10 upper deck windows, at least on the side taken in this photograph.
Photo © Joe G. Walker
But here in 1995, it is once again with three windows on that side!
Photo © Ryan J. Pearl
This more recent picture from 2004 confirms the three windows on the other side.
So what did they do to this plane? Did they install the ten windows on just one side or on both, and why did they plug them? Or did they rebuild it in the original skin configuration? I can't seem to see any plugs in the large version of the photo above.