The frame vin for your Ford....will be found on the passenger side, on or near the downward slope of the frame, behind the front passenger tire. And it will be on top of the frame rail itself. As for the ujoints... A good start would be to check your axle numbers. They are located on the axle tag attached to the differential (pumpkin). Or the numbers may be stamped on the axle housing, and the axle tube itself. In addition...you can get the numbers or code from the joint caps themselves, and look them up on this website : driveshaft specialist.com. It has a wealth of information concerning ujoints. Hope this information will help you. Best wishes for a successful repair.