55charliebird. The 'Bird crankshaft vibration damper assembly is a different animal from the y-block passenger car and truck units.
The donut weight on the 'Bird damper was originally secured in place by a vulcanized rubber material. The donut weight on the 'Bird damper has no timing marks on it associated with its position on the steel damper assembly. The timing mark on the edge of the inner pulley of the 'Bird damper is located related to the woodruff keyway going through the crankshaft mounting surface of the 'Bird damper. On the 'Bird damper, the timing mark on the inner pulley cannot move out of orientation with the damper's crankshaft woodruff keyway opening
After the donut ring on the 'Bird crankshaft damper is re-vulcanized to the steel damper assembly by the re-builder, the damper assembly should be dynamically balanced as the donut is likely not located in the same place as it was when originally manufactured. IF this re-balancing of the 'Bird damper assembly was not done by the company that remounted and vulcanized the donut in its correct location, it should be done by the engine re-builder.
Note that the damper re-builder in Oregon gives a lifetime warranty on their work and that Damper Doctor offers a three year warranty as I recall.
Hope this helps.
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York