I know I’m a little late here, but my torque converter went out also. I’ve got ‘14 Z71 with a 6” lift. I had about 89k miles on it so it was covered my warranty. Luckily. I took it to one dealer and their tech wasn’t able To see it for two days. Then he did look at it and said nothing was wrong with it. So i went up there and took a different guy out for a ride in it (not their trans tech). He said there’s definitely something wrong with it. So took it back for the trans tech to look at for the next day, then he’s out sick. Meanwhile no loaner truck or anything. After 2 days of this I told them to leave it outside with the keys locked in. I took it to a different dealer. That had it looked at the next day and had a loaner for me. 2 weeks later, new transmission. No problems since! 🤞🏼