vibration problem

If the vibration has the frequency of a heard of pissed off bumble bees, it is drive line related. If you can feel it more in the floor, seats and steering wheel, it will be tire and wheel related. I would nail down which it is FIRST, or you will be forever chasing your tail. I'll tell you something you can do YOURSELF that will cost very little and is very easy to do.

Get 4 steel hose clamps large enough to clamp around the drive shaft. Clamp all of them on with the screw clamps lined up together. Drive the car. Note whether the vibration is better or worse. Move the clamps 90* at the time until the vibration improves. Then, move the clamps 45* until the vibration improves even more. I think you see where I'm going. When you get the vibration gone, you can get a drive shaft weight yourself and tack weld it on the drive shaft.