here is the story.4.10 richmond gears,bad whine and vibration.3.73 ford gears,no whine same vibration.didnt have the vibration until the gear swaps.so,rotated the drive shaft in all five positions plus original,no better than it was in the original factory spot.took the bolts out one at a time and put a 3/8 flat washer on the them and reinstalled the bolt. not alot of change.kept doing this for each bolt but didnt move the shaft.got to the 5 th bolt hole and good gu be do,90% of the vibration was GONE!took the bolt out,added one more washer and if it got any smoother i would think it was going to fly all to pieces.i never would have believed this would work but it did.it vibrated real bad at 65 mph and now you would never know it did it.thank you joe lynch who ever you are,you are my hero.