As I indicated earlier, there is a TSB out for at least my 2012 for tcase noise...it sounds like a pinion bearing (coast sounds different from load). Under load you would think either the front end or the transfercase had a bearing about to implode. I don't use 4wd often, but when I do its for miles and miles of snow covered roads (which makes this noise particularly annoying) or towing/hauling heavy offroad (think cutting firewood).
I have nearly 100k on my 2012 and have had it in three times for the noise...the first was the TSB acknowledging the noise, the next was a TSB for a fix, and the last was a TSB stating the fix didn't work and there was no other plans to address the issue.
You can probably look those up, and see if they cover your truck.
I gave up after try number three, the fluid in the front differential and the transfercase look fine, I get very little wear metal on the magnets, and the noise hasn't gotten worse in that time. I'm not going to worry about it.
Sent from my SAMSUNG-SM-G900A using Tapatalk