Irritating Squeek

I have a 2005 F-150 2 wheel drive and it squeeks really bad. It's not a mechanical squeek but more like a loose body part. It squeeks while I drive. It sounds to be comming from under the bed of the truck. My work truck is a 2000 model F-150 with the same problem. Has anyone else came across this and if so how can I fix it.

you'll need to give more info.

where's the sound coming from?
it is constant? or just over bumps? cruising?

Here are a few things you might check since it sounds like its related to the body and not an engine squeak. i just got through fixing an suv that would squeak sitting still just from pushing down on the body anywhere. New shocks cured that squeak, but it still had squeaks while moving. Lubricating all the body mount bushings stopped most of those squeaks. Some of the bushings were really hard to get to to get any lubricant on. I use a chain lube with "Moly" in it made by Gunk which works pretty good. (part # L716) Ive tried the silicone sprays, and they work for a while but dont last long. The Moly seems to do the trick.

My old '77 F250 had an odd squeak from the back end that ended up being the bolt in the pivot arm for the back end of the leaf springs, the assembly had shifted from age making the nut end of the bolt scape against another piece of metal, I ended up stacking some washers under the bolt head to move the nut end away from what it was scraping on.

Check for nuts and bolts that are near other things they could come into contact with.

I have a 2005 FX4 4WD...Sounds like you have the same squeek I had. Mine came from the tail-gate striker plate to the bed of the truck. It is a rubber bumper that rests against the tail-gate when it's closed. A litte grease fixed it...and you're correct it was really irritating.