I've searched and can't find the answer. I have a 2014 Silverado 5.3 with 50k miles and just started noticing a loud creaking coming from the rear driver side brake. it happens when I'm at very slow speeds or even when I'm stopped (so I can't see how it would be something with the rotor etc). I've found threads about similar issues and have tried all the suggested solutions without success (clean caliper, parking drum, rotate piston, clean guide pins, etc). I noticed it is much louder and more regular with the engine running as seen in the video. Any ideas? Thank you in advance.