Here is another case study! 2016 Silverado 3500 hd built in Flint Michigan plant. Roughly 18k miles very loose steering. Dealer tightens lash bolt and lock tight. 27k loose again, dealer says first guy didn't do it right, re tighten and lock tight. 35k loose again. This time I looked underside and see small fluid leak from steering box. Dealer replaced steering box today, so far so good. Will edit post if it gets loose again.