I had it checked by a mechanic. He says the brakes are fine with no problems and that the difference in resistance in the front wheels is not uncommon. He thinks the noise could be caused by humidity or dust buildup. It only seems to be making it after driving the car for a while and then after waiting a few minutes, it stops when I drive it again. I am going to do another test in a few minutes in 2 or 4 wheel that isn't on gravel (going to find an empty parking lot that I can roll it at low speed to listen for it). It did it tonight after washing the truck. The brakes aren't on fire, so that rules out a caliper. Maybe it could be humidity or from the traces of water left over from the wash since I did wash the brake rotors, wheelwells and undercarriage as usual. It has been raining a bit here almost every day, so could this be water related?

The brakes themselves are fine and are actually working better than usual. I just drove it 140 miles on a trip tonight through the mountains and I even managed to avoid a crash with a deer going around a blind corner at 50mph. I hit the brakes and almost caused the truck to fishtail to avoid slamming into it.

 

I did the tests in a parking lot and could not make it make the noise at all. Maybe it is water/humidity and/or heat related since I only drove it 5 miles at 30mph compared to 65mph earlier in some places. I did put it in 4 wheel and while it was difficult to engage, the only noises I heard was the usual groaning noise when I made a shallow turn on pavement in 4 wheel and it started to bind, but I stopped as soon as the groan started. It also did grind a bit when I pulled the cable with it in 2HI and it wasn't fully locked in, but I also stopped as soon as I heard it and pushed the cable in, put the t/c in 4hi and tried again.

That 4x4 engagement test was also to make sure the 4 wheel was working at all because I know I am going to need it this weekend. The whine noise wasn't there and it was totally silent driving forward in 4HI and all the time in 2HI.