Sadly, I cannot offer any help.
I don't have experience with lock cylinders.
The closest I have come is replacing a ignition switch on a '85 Chrysler.....but that did not involve anything with the lock cylinder other than disconnecting the lever between the 2.
On the Windstar, I tried to show some detail in my pictures from my replacement of the "multi-switch"
Maybe a locksmith could offer some help?
The part you circled looks like some sort of key.....that would rest in a notch to hold it in place.