Professional Products 6.9 Inch Damper for Pontiac V8 326/350/389/400/421/428/455 features the Pontiac damper which is dimensionally the same as the 1969 through 1979 O.E. production dampers. In order to fit this damper to a 1961-1968 engine, the use of a 1969 or later timing chain cover, water pump and related accessories are required. Unlike some competitive dampers, our models include the tapered machining on the outer inertia ring which allows the use of the stock pulleys. It includes 60 degrees of timing marks and engraved marks every 90 degrees.