I have a vibration in my 06 lbcc lbz that is very noticable at speeds around 60 and really bad at 55-65 under moderate load(26ft enclosed car hauler(aluminum) with 4 sleds(about 6000lbs)). It really comes up through the floor and I am guessing that is due in part to the multi-piece driveshaft. I am going to take it in ASAP as I have only 10,000 miles, just looking for any other experiences. Oh yeah, it has been there since new.:mad: