1995 Ford Explorer Like riding in a boat.

Recently I noticed that my truck is rocking back and forth while cruising down the highway. I've experienced this before when I had low tire pressure, so I've double check all 4 and it's good. I then put it up in my garage and found a 8"-10" bar hanging just behind the front tire. The top has a hexagonal bolt head with a black bushing on top, the bottom looks like it has been sheered off, but I can't see where from. I've not noticed any other issues with steering or handling. I can't find any diagrams on the web, and I have no idea what these are. Ideas?

Thanks.