Hi RC I have a 21 5.3 sierra with 12,000 mi and I’ve noticed multiple times when I come to a light I feel a slight rumble under my seat and a little rattle behind the center dashboard. I explained to the service advisor on my last service what was going on but i was told no light no issue so far I’m the only person who feels the shake and until coming across your post I thought I was crazy. Do you happen to know what service bulletin I need to look up so I have some proof of my issue?