To add to our growing body of knowledge, the first thing you should do about a front-end rattle is check/replace your stabilizer (sway) bar and end-link bushings. It's a cheap, simple repair to try before tackling serious stuff like ball joints and control arm bushings.

In my case I had a rattle that would continue for a millisecond after I hit a bump, like an aftershock. Underneath the truck I could find nothing visibly wrong with the sway bar or the two end-links. However when I took the end-links off I could see that the big stud bolt on the driver side was rattling around in the metal tube because of how the bolt was worn. The end-links were cheap aftermarket parts, so I sprang for some OEM end-links and the big bushings that mount the sway bar to the frame. Parts came from Fordpartsgiant.com. Replacement was a piece of cake. Wow what a difference! Bumps are now just a muted rumble, like a new vehicle would make.