Due to Ford production tolerances, the width of the framerails in each car can vary. If your car's rails are considerably narrower than the chassis-mount U-brackets, use the provided spacer plates between the framerails and the flange of the U-brackets. This reduces how far they have to pinch inward when the bolts are tightened. These plates may or may not need to be used on the inboard sides of the framerails. Our car needed a plate on each of the outside flanges of the U-brackets, but not the inside. After all the holes are drilled and necessary spacer plates are in place, torque the 3/8-inch bolts to 47 lb-ft. The frame inserts allow these bolts to be firmly tightened without collapsing the framerails.