I had the same problem with my 05. Once I hit 60 on the hwy this loud howling/whining sound would blast from the back end, but only when accelerating. If the sounds is just when coasting it's the front pinon bearings, only when accelerating it's the rear.
I just finished (2 days ago) swapping the pinion and carrier bearings. Autozone carries a nice kit from Timken for $95 that includes all 4 bearings with races, new seal, new pinion nut, gear grease to check wear pattern, and blue RTV. It's a PIA job but doable. Make sure you have tall jack stands bc you'll have to get it up high enough by the frame so the axle can drop to pull the carrier.
The bearings themselves need to be pressed on and off, I took it to a local shop and they did it for $20 in about 15 minutes.
All told, keep in mind this was my first time messing with the gears at all, it took me about 10-12 hours over a couple days.
You'll also need to get a race driver, Autozone loans them out, to seat the new races. There's several videos on youtube that I watched to get an idea of the job beforehand.
EDIT: Also be sure to get axle grease to grease up the bearings before you put everything back in the pumpkin.