drive line vibration, 72 LB

[dukcaln]

so I recentley swapped to a TH400 and bought a used two piece driveline with carrier bearing... it all looked and felt solid. Swapped the rear ujoint to a combination joint 1310/1350... got the truck running after putting a different motor in at the same time. I believe I have vibration from the drive line, at least it feels that way... have a slight vibration up to 35mph then at 55mph it is pretty noticable...... was not like this at all with the two piece I removed so I am assuming it is the used two piece I got.

I was told to take the two piece shaft apart at the carrier and rotate it 180 and put back together and see if that helps or changes it.... any other things to look at?

Should I just take it to get balanced?