REAR DISK BRAKES HUMMING

i didn't see what rear you're running, so i'm going to ***-u-me that you've got a 8.75

however, ifin' you have a dana or 8.25 it's possible that your axles need to be "shimmed" a little tighter with with thicker c-clips to help eliminate some of the play and prevent the rotors from excessive movement. to note, this is also possible on the 8.75 axles, but a lot less likely.

but more than likely, it's something dead simple like the rotor needed turned or the brake pad friction material chamfered, anti rattle clip re installed, squeak shim de-squeaked, things of that nature.