• Press fit rear seal to engine block & crankshaft for proper fitment of inner & outer seal body • Services GM/ISUZU 6.6L Duramax 2001+ GMT800, 2500HD & 3500 • Installation instructions: Set new seal on inner body of tool. Attach outside ring of tool to the end of the crankshaft assembly, turn forcing screw to press in new seal • Compare to GM Factory tool J-44642