Vibration from drive shaft

[newlano]

I have an automatic 1991 525i. I changed my center support bearing on my drive shaft, after replacing the drive shaft there is now some vibration coming from it. We had to bang on the drive shaft very hard to get it to seperate into two pieces in order to install the new center support bearing. My drive shaft has the bolt in the center of u-joint. Do I need to get the drive shaft re-balanced and do you have any idea how much this may cost ?
Thanks for all suggestions!