To both
Chu Chu and
tdracer, thanks for the input. I found on the Boeing site they had this to say,
The Dash 80 prototype led to the commercial 707 and the military KC-135 tanker. Both planes shared the basic design of the Dash 80 but were very different airplanes, neither one being a derivative of the other.
Elsewhere I found that the only thing they shared was the basic wing box.
https://www.nationalcoldwarexhibitio...-stratotanker/