HomeAll RepliesReply To: 2021 GMC Sierra 1500 AT4 Lifter Collapse Reply To: 2021 GMC Sierra 1500 AT4 Lifter Collapse Sponsored July 16, 2024 at 8:02 pm #822101 Parts Man1Participant I wouldnt have any concerns about the techs who do the repairs Sponsored Subscribe to GM Authority For around-the-clock GM news coverage We'll send you one email per day with the latest GM news. It's totally free. First Name Last Name Email Address Subscribe via Email Leave this field empty if you're human: Sponsored