If you're installing a new rear Crankshaft Seal during a complete engine overhaul, begin by removing the transmission. Next, take out the driveplate. Carefully pry the Crankshaft Seal from the rear cover using a screwdriver, ensuring not to nick or scratch the crankshaft or the seal bore. Note how far the old seal is recessed into the housing bore for proper installation depth of the new seal. Clean the seal bore in the block thoroughly with a shop towel, removing all traces of oil and dirt. Lubricate the outside diameter of the new seal and install it over the end of the crankshaft, ensuring the lip points toward the engine. Ideally, use a seal installation tool to press the new seal into place; if unavailable, a large socket can be used to drive the seal squarely into the bore and flush with the rear cover. Finally, reinstall the driveplate and then the transmission.