I believe the C135 (KC135) was originally called Boeing 717.
True of False?
I believe True, the KC had a smaller diameter fuselage than the later 707. The airlines wanted 6-abreast in coach and the KC fuselage wouldn't allow it. But by the time the DC9-whatever came along, nobody remembered the original 717, so they used that number. Engines never had anything to do with Boeing's system.
GF