I did read somewhere that the carrier bearing will cause a vibration if not aligned left to right. The procedure was as follows:

Tape a string to the center of the bottom of the differential flange.
Run the string to the bottom of the transfer case flange.
Loosen carrier bearing and align the center of the bottom of the bearing with the string.

I tried this on my truck and it is very difficult to tell where the center of anything is. I did align it but my vibration is still there. So I guess the advice the others gave is right on the money. I would think it would help wear issues a bit if it were way off.