Wow- This is depressing. Wish I had found one of these forums a couple weeks ago. Just purchased 2019 Sierra 1500 5.3 and everything seemed fine for a few days. Then over the weekend slowing to a stop she came out of second very late (at least I think it was second) and clunk. I've driven pickups my whole life and this ain't right. I've read somewhere that swapping the fluid out helps but that seems to be a stretch. Bringing it in to dealer tomorrow wish me luck. I plan on towing with this truck and was wondering if this becomes worse while towing.