The OTC Crankshaft Rear Seal Installer, No. 6741, is a two-piece tool that mounts to the crankshaft, placing force on both inner and outer seal bodies and is designed to press fit the seal properly without misalignment. For use on 2001 and later 6.6L Duramax diesel engines found in GMT800, 2500HD, 3500, and GMT900, GMC Sierra HD and Chevrolet Silverado HD, as well as 2006 to 2016 Chevrolet Express and GMC Savana.