Shown above is damper #3512017, commonly known as a "six-pack" damper. This damper can be easily identified by a small .210" thousandths thick elliptical weight attached to the center hub. This version was used in '70 and '71 and has the offset pulley bolt pattern. Be careful not to confuse it with 3614372, which was used only in '72 and looks similar except for having a symmetrical pulley bolt pattern. The weight on the 3614372 may be slightly thicker at .255", but we have not been able to verify this.
Even though these dampers have an elliptical weight, they were never used with any cast cranks. These dampers were used with steel cranks and "six pack" (2951908 casting #) rods. The extra weight is to offset the added weight of the extra metal in the rods and pistons. Another important fact is that even though six pack rods continued to be used up until 1975 in HP and truck 440's with steel cranks, they did NOT use this damper. As you can see from the chart above, any 73-75 steel crank 440 (with either six pack or standard rods) would have come with the 3614371 damper. We have found this to be absolutely true.
