I noticed that F100s seem to have two different types of exit/airstairs:
#1 - Built in airstairs, drop-down door
Photo © T.Ashoori-Iranian Spotters
#2 - No airstairs, slide-to-the-side door
Photo © Michael Fritz
Were these customer options? Or do older F100s have different door arrangements to newer ones? Is one arrangement more popular than the other? Can the drop-down door F100s be connected to airbridges?