[lust4speed]

This reads about the same as following the pea moving around under walnut shells. I probably missed it but most shops in my area zero balance cranks for a performance build. It seems that the assumption was made that the crank was still needing the 6 inch ounce external balance, but the vibration indicates that a stock flywheel is causing problems.

There were only two choices that should have been made by the original builder - either stock balance retaining the external balance or a full internal balance requiring a neutral balanced flywheel. If a presumed good external balance flywheel vibrates, then the only other choice should be a neutral balanced flywheel.