06 rcsb, new driveshaft balanced and works great. All the sudden i have horrible vibration at 35-45 and then again after 70mph, i have had the problem before but was quickly fixed due to simple inspection and my damn bolts at the rear to the u joint started backin off. Heres what i see now and im not sure if this is suppose to be, my u joint has play in the bearings side to side by about a 8th inch....is that normal??? Do i just need to replace the u joint with new....keep reading my other replies to help further

 

nope its not normal, replace them.. id replace front and rear

 

Thanks Skeet i figured so but maybe there was something else goin on with that.

 

Ok so i pulled the shaft and i know u say to replace both joints but only the rear had play in it.....its not clear to me why, they r both new joints and they seem fine but its almost like the rear isnt the right size or somethin.....why does it have this play in it side to side inside the rear yoke to the differential?? its like its too wide compared to the u joint,