I thought I had posted this already, but can't find it. I have a vibration that is selective to speed. I have all new steering linkage, new ball joints, and several all wheel balances, with no help. I had to lower the rear of this 2008 4x4 ST crew cab to fit my 5th wheel. I did the lowering by reversing the spring pack. Could that have caused the vibration?

 

Is it only when you are accelerating? U-Joints maybe?

 

I did check all the U-joints and all seemed fine. I am at a loss as to the cause of the vibration. Tires are new BF Goodrich TA's and also seem OK.