I have an 05 auto with 33000 miles, I used to have a powerpup on it but I haven't for a few months. The other day when I was driving I noticed a vibrationjust cruising 60 on highway. I only feel the vibration at higher speeds when the TC is locked. I was thinking it could be a u-joint going out, what do you guys think?

 

Well, it's possible its a U joint. I have some vibration problems and one was a little rust in between the right front rotor and hub in witch made my wheel look wobbly on the highway! Also, one of my front U joints is mis alighned a tad-bit so it vibrates on the highway also.(crappy front end design by Dodge). Good luck in finding the problem!