Thoughts on vibration

OK so a bit more history if you will,we just built our stroker combo,see 340 stroker build will this make our goal and got 3 passes on it found the converter is a bit loose and running more rpm than i want.Run good except for too much trap rpm,no vibrations. Enter a new 4.10 gear set up,different case and all new pieces,bearings spool ring pinion,yoke and set up by our usual guy that also did the 4.30 coming out.Reinstalled and 1st pass out vibration/harmonics idk is there made 2 more passes no real change.I did notice after 1st pass one u bolt for the ujoint had more thread past the nut on the top than the bottom,was able to loosen nuts a bit and got it to move so apprx same but did not remove shaft,no difference.ujoints new at start of race season so was there 1st week and now have 6 runs.Probably leaving something out still so ask away.