2014silveradohighcountry

I have a 2014 Silverado high country and have a clunking noise from the rear. (Have an appointment Thursday). Was there a service bulletin on this? Very pronounced in reverse and when going forward at slow speeds. In addition have had a clunk several time at around 45-55mph. I previously owned a Nissan Titan for 3 years and had zero problems with it. My Silverado has 12000 miles and has had many issues. Reading the other comments seems like an ongoing problem. I think I bought a $55000 pile of junk!