Hey B65FF ..
When JB redid my 390, they had to use the Performance damper 'cause they couldn't get a stock one. For all the hoopla and cost, and OFFICIAL racing tag in the box, the bloody thing was no good. It wobbled like crazy. Had to take it back and show them. I was worried that the end of my crank was bent but it was a "rare" defective damper. Replacement was fine. Just don't assume that high quality parts are always perfect all the time.