So meant to follow up with this. I've had more time in the truck and now have the symptom down pretty well.
1) sharp turns, the kind you make hugging a curb at stop sign.
2) foot on the accelerator - initially I thought this was about turning up hill. No, the reality is that a lot of the time when coming from a complete stop I coast through most of the turn. Any turn, up hill down hill, level, as long as I maintain accellerator coming from a dead stop, I get the vibration. I saw it turning up hill because in those scenarios you are less likely to coast through the turn. When you feel it the instinct is to take your foot off the accelerator, and when you do, the vibration stops at that moment...if you straighten your wheels (complete the turn) and then put your foot back on the accelerator the vibration is gone. If you complete the turn - the vibration will leave when you straighten out.
3) left or right doesn't matter - I make more tight hugging right turns than left - which is why I thought it was side specific initially.

I don't simply feel the vibration in steering wheel, I feel it in the seat of my pants. I'm always reminded of the etching in the concrete on the service lane of freeways - the so called "drive by brale" line that wakes you up if you drift over there.

Speed - engine or wheels vary with vibration? - this is pretty hard to test, the sharpness of the turn would make it unsafe to determine if the problem happens at other vehicle speeds or RPM. I can only tell you it happens to me in first gear, around 10mph, around 1500 RPM....if it is happening during less sharp turning or higher speeds (lane changes, freeway on ramps/off ramps) I simply haven't experienced it yet. Most of my driving is around town - 15 minutes of stop lights every half mile and 35-40mph speed limits (if it's not school zone time). About once a week I drive across town 20-30 miles on the freeway, but haven't noticed/felt it then...

I jacked the truck up and tried rocking the wheel vertically - no play on either wheel. With the tire on I spun both front drivers and passenger - it spins, though I hear some friction...not sure if it's normal..it's in one of the videos linked above. I spun it wheels with steering turned in either left or right made no difference.

So - doing a little further googling...wheel bearings seem to be a common cause...I thought great...front wheel bearings are greasable...uhhh, no. Not on 4WD...so I'll have to put some skin in the game if I really think it's the bearings.
The good news is, I don't have front wheel ABS (I double checked.) so the bearings/hubs are a bit less expensive, $110 or $160 for the premium brands.

So looking at diagrams this looks like a pretty easy 'bolt on' part that should be pretty simple to remove and replace. However, there's a lot of rust down there. I have a feeling it's going to be a PIA to get off and on.

 

Does your truck have the limited slip rear diff? That sounds a LOT like an LSD without friction modifier.

 

It does. I used a lsd additive off the shelf from orielllys when I drained and filled a couple weeks ago.

I used 2 bottles, 8 oz of
https://www.oreillyauto.com/detail/lubegard-4125/chemicals---fluids-16461/grease---lube-16582/gear-oil---additives-16905/gear-oil---additives-19589/limited-slip-friction-modifier/42851/4409964

With the balance of 75w-140 synthetic.

I thought missing LSD additive might be to blame so prioritized that rear diff change...but alas she grumbled before she grumbles after.

I'm thinking about taking her some place for a professional opinion. I can follow instructions in manuals to change parts but diagnostics requires experience.

 

Well, according to everything I can find, that should be correct. I did note that some folks had issues with aftermarket friction modifier, and changing to the Mopar stuff helped....... Will that make a difference for you? No clue.... Might try adding another couple ounces of friction modifier, and see if it makes a difference?

 

I filled till it trickle out. So i would have to pump a little out. I'm going to get the suspension checked(free check) if everything checks out I may go as far as drain and fill, again, this time ordering the mopar stuff. While the cover is off any harm in spinning the wheels to better inspect the diff(up on back stands). Last time I did it with truck on the ground so just looked at the teeth in front of me.

 

Yeah, you can do pretty much whatever ya want while you have it in the air. (don't run it with the engine though.....)