Drive train vibration

jist joined the site and my question is I recently replaced the u-joints on my 04 and I am experiencing a vibration starting at about 45 mph and continues to get worse as I continue to excelerate. Thinking it might be in the rear end but after reading about some of the other comments I’m curious about the drive shaft balancing not sure how to go about that

 

Did you mark the drive shaft and put it back in the same location? If not it could be a balance issue.

 

99% of the time it wasnt matched back correctly after removal (see RonT4R comment). If you can find a place local to balance it usually runs $100-$200 to balance it. Depends on what you have the do to it.