To remove the rocker arm cover(s) from the cylinder head(s), detach them starting from the front of one cylinder head by removing the rocker arm fulcrum bolts and storing them in marked containers for reinstallation in their original locations. If only the pushrods are being removed, loosen each bolt enough to rotate the rocker arms to the side for pushrod removal. On Mustang models, lift off the rocker arms, fulcrums, and fulcrum guides, while on Cobra models, remove the roller rocker arms and pedestal assembly, ensuring all components are stored properly. Check each rocker arm for wear, cracks, and damage, ensuring the pushrod end holes are open. Inspect pivot areas and fulcrums for wear, replacing any worn or damaged parts, and check pushrods for cracks and excessive wear. Before installation, ensure both lifters for each cylinder are on the base circle of the cam lobe, lubricate the lower ends of the pushrods, and apply grease to the valve stems and pushrod ends. For valve adjustment, be aware that 5.0L HO V8 engines have a different firing order than 4.2L V8 and non-HO 5.0L V8 engines, requiring a specific adjustment sequence to avoid damage. Using a lifter bleed-down tool, check the clearance between the valve stem and rocker arm with a feeler gauge, noting the results for future reference. Position the number one piston at TDC and check the specified valves for both V6 and V8 engines, rotating the crankshaft to check additional valves as outlined. Clearance can be adjusted using different length pushrods if necessary. Some early 5.0L V8 engines may have adjustable rocker arms, which should be checked for clearance in the same manner, adjusting as needed by turning the rocker arm nut, following the firing order for the adjustment sequence.