Do you have a 300-6 in your F250? I'd start at looking at Haynes or Chilton's manuals. There SHOULD be (never is when you need it) a label on the hood / valve cover/ or near the radiator that has a vacuum diagram. The dealership maybe able to help you if you give the information of the VECI label on you valve cover, don't forget the three or four digit code on the bottom of the label. Best of luck!