Thanks for your replies, Moses and Dustin.
Truck is not lifted. Around 185,000 miles. I do have an Edge Juice with Attitude. However, I am very easy on the truck. I generally have it on level 3-Drive. I have a truck camper and when it's on the back of the truck I set the level to 2-Tow. Again, am very gentle with the truck...never push the pedal hard or go wide open throttle.
I started to pay close attention to vibrations/sounds when I installed the new driveshaft around 1,500 miles ago. That's the first time I heard the noise, but, it is possible the noise was there before.
I have the old driveshaft and am going to swap out to see if the noise is still there and/or as loud.
I also ordered a wireless Steelman ChassisEAR http://www.steelmantools.com/wireless-chassisear.html . I'll put the clips/sensors on the differential near the pinion bearing, on the transfer case output shaft close to the bearing, etc,...to see if I can determine where the sound is coming from.
I do lock the hubs for a few miles once a month or so just to be sure front u-joints, differential and transfer case stay lubed, etc....
I'll let you know what I find out next week when I use the ChassisEAR.
Thanks,
Dave