Trucks been at dealer for over 2 weeks for tranny shudder and then they found collapsed lifter. Less than 20K miles. What is with these trucks? Dealer says there are no issues with them, even after I bring up all the bulletins. Seems a bit early for a lifter issue compared to everything else I've been reading. They claimed it wasn't AFM related....Anyone get anywhere with GM? I told them I wasn't happy a less than year old truck now has a bunch of issues and has been all torn apart.