I have gone through 3 transmissions and 2 torque converters and I still have the shudder problem and this is just on my 2015 Silverado Z-71 6.2 with 182,342 miles. The dealer is kind enough to replace under warranty. I also have a 2018 Silverado Z-71 6.2 8spd that has the same shudder. Fluid has been changed and next step is torque converter.
I have a 2008 Silverado Max 6.0 Z-71 4 x 4 with a 4L70E transmission and I can positively tell you that your second gear has gone as my truck is at a local Chevrolet Dealership in Kenner, La waiting for the replacement transmission to come in. My truck has 489,674 miles on it and the current transmission has 212,028 miles.
I have a 2015 Silverado Z-71 Crew Cab 4X4 and the paint is flaking off of the rear drivers side door and bed. From all of the post's, GM needs to correct problem for us.