grinding/growling noise driving me crazy! HELP!

[knightowl73]

Ok so ive been hearing this growling noise coming from my truck while im braking, so i took the liberty to change the front pads, since i never had. the indicators werent and looked like they hadsome life but i still changed them, and nothing changed with the noise. so i thought maybe the rears. i jacked up the truck and took the wheel off to check which width rear brakes i had, but damn the shoes look damn near new in the rear, i recently put this rear, so no problem there. thought they would most likely be due for a change. so after all this i still need to bleed them a il more, seems as if there is still some air somewhere, but i still have the noise. could this be my trans or rear-end? i only hear it when im braking though. ive even let someone else drive my truck and i listened as they left and came back but still only heard it when the brake lights were on so it leads me to beleive somewhat that it is still something with the brakes. rotors and drums looked fine.

anyone lse ran ino this problem? im just stumped that i cant figure this out, thought it was a simple indication of needing pads n shoes but i was wrong.