new to the site...need help with a vibration

I have a 04. 5 2500 CTD quad cab 4x4. Skyjacker 2. 5 lift springs up front, add-a-leaf in the rear. Cooper discover ATR 315x70x17 tires. Recently my truck has developed a front-end vibration. I thought it was the tires because they were starting to cup slightly. My symptoms are a droan while driving at moderate speeds and a vibration when coming to a stop that feels like im running over wash board pavement which can be felt thru the floor boards and seen in the shifter, (6 Speed) which is is kinda the odd part to me. I had my tires rotated hoping it would fix the problem and it did nothing. Thanks in advance for everyone's help and I'm glad to be apart of the site.



Josh

 

Maybe a bad u-joint?

 

thats what i was already thinking. . wanted someone else to say it before I suggested it. My truck is going to have to go to the shop tomorrow before something comes apart. . I think the u-joint is bad on the front drive shaft coming off the transfer case and it is diffently bad at the drivers side front tire.