Still unresolved, but the vibration has noticeably increased in the last ~1000 miles since my first post. However, just for "fun" I engaged 4WD while it was vibrating and it made an immediate improvement - which tells me that the cause is definitely in the front end - most likely in one of the rotating components (wheel hub, CV axle, etc.) I'm expecting to tackle repairs starting this coming week.

Regarding the "death wobble" - One thing I saw somewhere was that it only applied to "heavy duty" trucks - which would rule out the 1500...

 

Yeah, Death Wobble was pretty much restricted to the solid axle front end trucks.

 

https://kevinsoffroad.com/blogs/kevi...-wobble-causes

This site has an overview...

 

I had two vibrations,on an '03 1500, front driveshaft worn out and separately had a CV joint/axle fail not long after replacement. Got a smoking deal on a US Gear rebuilt shaft like +-90USD through Amazon, even with shipping to B.C. still a smashing deal. Bought the only two they had, sent one home to Nevada. The driveshaft problem was accompanied by a small tinny light knocking sometimes.
Bought quality axles I thought from NAPA. They replaced under warranty, but I would never ask them again. The cause is as much due to hard use and the front end lift I put into the torsion keys. However, it took 40k miles with lift on top of 230k original miles to kill the originals.

 

Some auto shops just can't be trusted - I found the trouble: It was the right (passenger) CV axle. The (inner) sleeve that slips over the differential's right axle shaft was EXTREMELY loose! So loose that I'm surprised that it didn't fly apart! the shaft had worn down to ~ 1/8" smaller than the sleeve!

 

And that didn't make any noise?????

Holy smoke.

 

Lotsa noise - Lotsa vibes, but the shop said they couldn't see any trouble! Instead, they re-balanced tires a few times - each time the balance was off. Then they said it was probably a bad tire - out-of-round or something, so they replaced all 4 tires at no additional cost - no difference. Then they said it was a warped wheel, so they replaced all 4 with new. No difference. Since I took all their recommendations and nothing was resolved, the owner ate the cost. When I finally to it upon myself to investigate and found and fixed the cause, I informed the owner of the shop of my findings and he just replied with a "hmph".. I took that to means that he was totally embarrassed that he missed something as obvious as that - which he should be!

 

Think I would be lookin' for a new line of work......