The Chevrolet Performance Heavy-Duty 8-Inch Nodular-Iron Torsional Damper is an off-highway design for competition small block V8s in racing classes which permit the use of production-type balancers. This damper was originally used in NASCAR competition and offers an extra margin of reliability at high rpm with a high-temperature elastomer ring. The hub and ring are balanced separately and then balanced as a unit.Its nodular iron inertia ring offers an extra margin of reliability at high rpm. This item can be identified by the ID #4709; with it's outer ring marked "MALL." The timing mark is located 10º before keyway center line.