Section 136 (Driveshaft -- F150): Overhaul: Notes
WARNING: This page is about a different car, the 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
DO NOT, under any circumstance, clamp the drive shaft or the coupling shaft in the jaws of a vise or similar holding fixture. Dents or localizing fracture can result, causing drive shaft failure during vehicle operation.