Help.....not familiar with Fords, but done my share of suspension work on my BMW E36.

My wife's 99-Expedition 4wd has the front passenger tire going very bald on the outside of the tire tread all the way around the tire.

I did notice that the sway bar (end link) connection was broken off on this side. I replaced this already.

Could the sway bar link be the culprit of the wear on the outside of the tread? Or, could there be an issue with ball joints or other worn suspension components?

Any idea on how to test? Pictures, etc.?

 

I don't think the sway bar link will cause pre-mature tire wear, just excess body roll. If it's just one tire, I'd look at toe(bad tie rods) or tire pressure or possibly ball joints.