Just found out the thread I started would be helpful in this thread: http://www.gm-trucks.com/forums/topic/173454-strange-noise-coming-from-rear-end-passenger-side/
I scheduled mine for the second time. They scheduled me for the 18th and said I need a loaner car since they will have to keep it a few days. I had it "fixed" last year and its doing it again worse this time. I'm hoping this works.
I bought my 2014 in August of 2013 and when I hold the answer button on steering wheel the OnStar voice keeps coming on, it's not Siri. My audio soft version is 000464.