Its easy, look under the truck on the driverside inside frame rail area (between frame and clutch housing). There is a rod with a bullet shaped head that pushes on the arm that goes into the clutch housing. This is what controls the throwout bearing. What you want to do is loosen the nut of the back of the bullet shaped part so you can unthread it until the slop is out of the pedal. Grab the pedal and make sure there is about 1/2" of play in both up and down direction so you know it free and not engaged, 1" is OK too. I've seen some clutch rods not long enough and have to be lengthened to get the play out of the pedal, espacially with a worn out clutch. If in doubt have someone push on the clutch pedal while you are under the truck and you will understand whats going on...
