Ugh! Same here. My 2018 Z71 5.3 is at 90K miles and I have the lifter ticking. I just bought this truck 3 months ago from a dealer. They said they would replace the bad lifters but not all of them and I would still have to pay. I am opting for my local mechanic who is really good and trustworthy. He is going to replace ALL the lifters and add a tuner. I am praying that is the fix and there isn't any other damage to my engine. The dealer is now offering to try and help financially since I've only had the truck 3 months. To be honest, I think they knew they were selling me an issue. My first and last GMC truck! I've always had Fords or Dodge.