Should have started with that.
It's a 2014 Sierra Denali 1500 with the 6.2. Crew cab, 5'8" bed, about 118,000 miles.
The noise I'm hearing can be heard at 2 and 14 seconds in the video.
I noticed the tach bouncing but was sure if that was normal for this truck or not. I'm climbing a slight hill in the video and the bouncing doesn't seem to be tied to the noise but it could be related.