Thank you all for the replies!!!
Sorry to get back so late. I'll answer in order.
ZeeJay1997: "do you have 4wd? is it front or rear?"
Yes, full-time 4x4. The sound is coming from the rear, but I can feel the grinding all the way on the front floorboard.
Myusernam1674: "maybe it's a pinion bearing? Or wheel bearing?"
Yeah, that was my thought. I was hoping the sound would be more conclusive toward something else though, because it seems like most people with a pinion bearing problem have more of a whine than a whir and scraping noise.
Uniblurb: "All your fluids at the correct levels in the axles/transfer case?"
Yes, my fluids are all good. I have been feeling my differential after trips. It seems like it is in the normal temp range too. I just drove from Florida to Colorado though, and I don't think I really had the sounds on the trip, but they may have just been subtly getting louder.
Thanks for the extra info. Based on that it would seem like it is the front pinion bearing, but my front differential isn't making the noise. I know also that usually the drive shaft feels loose to the touch when the bearings are going bad, and mine feels very solid, and no fluid is leaking.
Thanks again for the answers! If you have anymore ideas, please share!