Raise the vehicle and support it securely on jackstands. If there's a leak, it's an ideal time to replace the front pump seal/O-ring for automatic transmissions. Remove the pressure plate and clutch disc for manual transmission vehicles, and consider checking or replacing the clutch components and pilot bearing. Look for factory paint marks indicating flywheel-to-crankshaft alignment; if absent, use a center-punch to create alignment marks on both the flywheel/driveplate and crankshaft for correct reinstallation. Remove the bolts securing the flywheel/driveplate to the crankshaft, using a screwdriver to jam the flywheel if the crankshaft turns. Carefully take off the flywheel/driveplate, supporting it while removing the last bolt due to its weight. Clean the flywheel to eliminate grease and oil, inspecting for cracks, rivet grooves, burned areas, and score marks, with light scoring removable using emery cloth. Check for cracked and broken ring gear teeth, laying the flywheel on a flat surface to check for warpage with a straightedge. Clean and inspect the mating surfaces of the flywheel/driveplate and crankshaft, replacing the crankshaft rear seal if it's leaking before reinstalling. Position the flywheel/driveplate against the crankshaft, aligning the marks made during removal, and note that some engines have alignment dowels or staggered bolt holes for correct installation. Apply Teflon pipe sealant to the threads of the bolts before installation, and use a screwdriver through the starter motor opening to prevent the flywheel/driveplate from turning while tightening the bolts to the specified torque. The remainder of the installation follows the reverse order of removal.