The vibzzz are killin me!

Start taping fender washers to driveshaft. Do one and see if it does anything. Move in 90 degree increments until you feel a difference. You can use a large hose clamp too. I thought I read somewhere it would find its own balance if you didn't tighten real hard, sort of let it rotate stiffly. Or drill and pour a quart of atf into the drive shaft and weld back up. Sounds strange but its also supposed to calm harmonics (TCI rattler balancer comes to mind) . Never tried the fluid...but the taped weights was how the drive shaft guy did mine until it balanced then he tacked them on.