367-80 was a prototype and development aircraft, not a production unit, and as such it will have had hundreds of different mods and variations done to it during its lifetime. Nowadays this tends not to be done so much because so much development is simulated on computers, but this was not the case in the 1950s.
Other prototypes have had much more radical changes than this done to them. A BAC One-Eleven prototype was sawn in two and a fuselage extension inserted. Then later it was cut again and restored to its original size.