Designed to mimic GM 88958607, these dampeners will fit any GM Gen III block with the holes already drilled and tapped. Engine fitment includes the popular LS1, LS6, and 5.3 truck engines. Dampeners will work with either single row or double row chains. The bolt spacing measures 2.1” center to center and the dampener is machined from high temperature, low friction nylon. Fully machined in the USA.