This is from our 2016 Suburban with the 6L80E transmission with 81k. It started to whine from the transmission and then we lost all our gears even reverse in just 5 miles from the noise starting. What was weird is that after turning it off and letting it sit it worked again but the whine was still there. Had it rebuilt and the shop said the TC was gone and the pump showed some wear. The fluid was changed out to AMSOIL ATL at 10k miles from new, then I did a pan drop and filter change at 36K miles. So this fluid had 45K miles on it. AFM was not disabled, but it is now. Seems this is an issue with these transmissions. The shop that rebuilt it said they do at least two a week. Interesting that this sample didn't show more than what it does considering the transmission went bad. Maybe because I didn't drive it once it showed signs of issues??