I just replaced my upper int steering shaft. I had a bit of a knock in the steering that was starting to drive me crazy. Nobody else could feel the knock because it was so suttle, but getting it new, I could feel the diff. Anyway it was the upper intermediate steering shaft, lucky guess. I have never seen one go bad in any Trailblazer. Now I have seen bunches and bunches on full size trucks, Impalas, but no Trailblazers. Just thought I'd share.