Seal between hub assembly/steering knuckle?

[TheCirque]

1997 Expedition 4wd: I pulled the bearing/hub assembly because of bad bearing. I wiped out the inside of the bearing pocket/steering knuckle and found what appears to be remnants of an o-ring. I cant figure out where it came from. Where does it belong?

I purchased new hub/bearing assembly but it does NOT include any new o-ring.

I cant seem to find any schematic that shows an o-ring.

Can anyone help me out?

Thanks

 

[DR3W]

Was anything tampered with by a previous owner with a lift or anything?

And idk to much abouty these 4x4 front hubs. Lol