18 Shifting Clunk into Drive

Curious for thoughts/feedback/suggestions on this clunk that I'm getting when shifting into drive. I've taken two videos combined into one - first part is from the driver seat, second part is under the truck.

Pertinent Information:

• 2018 Tundra 5.7L 4WD Platinum
• 106,000 miles
• Clunk only happens on fully cold start, only when shifting into drive
• Sounds like transmission, could potentially/unlikely be drivetrain

Detailed Notes:

• Video taken in my garage, backed in, sat overnight - so shifting straight into drive from park
• Transmission fluid drain and fill (not fluid exchange or flush) at 50k and 100k at dealer
• No real modifications to the truck (only mods are things like LED lights, auto-locking tailgate, etc - no lift or anything major like that)
• Not brake related - recently did 4 wheel brake job, clunk was happening before and after
• Not related to parking brake, happens on or off, didn't move, and didn't touch it in the video
• Doesn't clunk into reverse, neutral, or back into park
• Doesn't clunk into drive when warmed up or driven recently
• Clunk seems to only happen when shifting straight into drive, on a cold start, when the transmission engages - I am fully stationary in this video
• Truck drives normally otherwise
• Considering a fluid exchange at this point based on the clunk, but hoping for some sage wisdom or a previous/common experience