There two diffrent typewriters. Selectric used the ball, the Executive did not.
There were many many IBM models. AirForce had few, and generally only the cheapest, except for the General's Secretary.
Here is history of IBM typewriters, with pictures:
http://www.etypewriters.com/history.htm
Here is a picture of a 'new' executive:
Here is Old Executive:
You have stomped the ego's of many self-proclaimed
"experts"! :-)
LLS