I just had mine at the dealer yesterday for a front end squeak, it turned out to be loose control arm bolts. Made noise on bumps and if you bounced the front end up and down, but not when you turned the wheels. Hope this helps.
Check the steering stops. It's just a protrusion on the front cross-member that limits how far the steering knuckle can move while turning left or right (one steering stop on seach side of the cross member). You may need to crawl under the truck while someone turns the steering wheel from side to side, lock to lock. You will see where the steering hits the cross-member.
That contact point needs to have a dollop of chassis grease smeared on it.
The squeak or creaking sound is caused by your suspension going up and down while the steering is turn all the way to the steering stop. This causes the two pieces of metal to scape up and down against each other and create the squeak/creaking sound. The grease stops that. This is a very common problem with the Sport Trac.
Always look for the simplest problem to fix before you start throwing a lot of money at the problem.