Help With Drive Shaft Vibration

[1fstsierra]

Well comeing home from work thursday I got on my truck just for fun and broke the rear drive shaft. So I went to the junk yard and got me another one the carrier bearing is good replaced all the u joints and im still getting some vibration at 30mph its real hard vibration and up to about 80mph u can feal it preety good. Everything is bolted on rite drive shaft is strait the only thing that I have noticed is that the rear drive shaft at the rear end u joint u can move the drive shaft side to side and the clips that hold the u joint are nice and tight. Ive gone thru at least about 10 u joints and they all do the same thing from autozone,oreily,and advanced auto parts. Does anyone have any ideas on what this could be thanx?