I'm still waiting on the 2nd replacement driveshaft to get here, but this time it is being checked for the correct amount of grease on the slip yoke splines before it goes on the truck. I still stand by that my original and its replacement were from a bad batch that didn't have any/enough grease. I believe Dana is the vendor for these, so it's probably been a widespread issue (I think the Wrangler even had a recall for this or a similar problem). The dealer did grease my replacement two subsequent times, but the damage was likely already there from thousands of miles of driving without.
The second time the dealer greased mine actually made a difference - but it would still present the problem on occasion, albeit not quite as harshly as before. A buddy of mine hypothesizes that due to the extra long 2-piece (technically 3) shaft and 3.92 gearing causing some torque against the system, it might be inherent to the design. I suppose I will see when the new one gets put on.
FCA did provide me with an extended service plan ("warranty") as one of their offerings for help, so I am not overly concerned about going forward driving it at least. It seems to be an annoying problem, more so than a critical failure waiting to happen, at least for as long as I'll own it.