Need help diagnosing vibration

Hello all. Don't get to stop here often, but wondering if I might get some help in diagnosing a vibration I've recently developed in my 2010 DC 4x4 with 174k miles. I'm not a full-blown gearhead, but I've got a good basic understanding and willingness to troubleshoot.

The vibration occurs shortly after starting from a full stop, between like 10-20 mph, and then quickly dissipates as speed increases. It does not occur again until after the next full stop. It's mild but noticeable, and I'm concerned it could get worse. It feels to me like it's coming from underneath me (in the driveshaft?) or behind me in the rear suspension. When I tow my boat (4k lbs), it's more pronounced, but exhibits the same behavior. If I drop into neutral while in motion, and rev the engine, there's no vibration, so it does not appear to originate in the engine itself.

I took a look underneath at the center support bearing between the two pieces of the driveshaft, and I noticed there seems to be some play (see attached pic and links to video below). Wondering if this could be the culprit? If not this, then suggestions where to look? Transmission? Axle wrap?

https://photos.app.goo.gl/DVgfZWJVYZGxhdGTA

Thanks in advance for taking a moment to read and respond.

 

That center beating look beat to crap!
I would replace, and while your there do all ujoints

 

Sounds like a driveshaft related vibration. The carrier bearing in the video does look to have a bit more play than usual.

The fact that it changes when towing and the vibration goes away with no load, makes me think it’s driveshaft related even more.

 

Most probably Prop shaft components. Carrier Bearing and U-joints.

That Carrier Bearing is definitely shot. The replacement will require taking the center U-joint apart, so might as well replace all.