To remove the timing chain cover and, for 6.0L models, the oil pan, start by taking off the oil pump pick-up tube mounting nuts and bolts, then lower the pick-up tube and screen assembly from the vehicle, ensuring to remove the bolt securing the oil pick-up tube to the oil pump. Next, for 6.0L models, take out the oil pump retaining bolts and slide the pump off the end of the crankshaft. For 5.3L and 6.2L models, install special tool EN-51257 against the timing chain tensioner and the edge of the oil pump body, tightening the mounting bolts securely. It is crucial for 5.3L and 6.2L models that if the oil pump is removed without replacement, special tool EN-51267 must be installed to maintain alignment until reinstallation; otherwise, a new oil pump is required. After removing the oil pump cover, withdraw the rotors and clean all components thoroughly, inspecting for damage, particularly on bolt holes and splined surfaces; replace the entire oil pump assembly if any components are scored or worn. To install, prime the pump with clean engine oil while turning it by hand, then position the oil pump over the crankshaft, ensuring proper alignment with the crankshaft sprocket. For 5.3L and 6.2L models, maintain contact between the pump body and the alignment tool while tightening the bolts, ensuring no gap exists. Install and torque the oil pump mounting bolts, then attach a new O-ring to the oil pump pick-up tube, fastening it securely to prevent air from entering the oiling system. Finally, align and install the timing chain cover and oil pan for 6.0L models, complete the installation in reverse order, add oil and coolant as needed, and run the engine to check for leaks and oil pressure.