Trans, transfer case or rear?

[Silverado315]

First post. I am at a loss on what this could be since the dealership claims it is normal. It is not. Many of you seem to be quite knowledgeable so I am hoping for some ideas and thoughts. Between third and fifth gears, when I hit the gas and it shifts back up 1 or 2 gears, and I have to quickly let off, there’s a nasty clunk/bang that jolts the entire truck forward. Dealership originally said it was in the rear. They replaced the carrier bearing and had to reset the preload. Seemed better for a few months. Now it ya doing it again but worse. Now they’re claiming it to be normal. Anyone have this issue or have an idea of what it could be? 2015 Silverado 4x4 4.3 6 spd 

[Supreme Pizza]

Free-play in the drive-train. Put the rear axle up on jack stands, block the front wheels, put the trans in park, and start rolling the rear tires forwards and backwards. There will be slop between two parts. Could be the diff, the U-joints, etc. 

[Dnt]

Probably just  a bad case of Axle wrap, these 1/2 ton trucks have long weak flexible leaf springs that allow a lot of axle wrap. Have your local speed/lift type shop install a set of traction bars and you should be good to go. That will help you to do some awesome burnouts too........