I've dealt with this noise ever since I purchased the new 2017 Silverado. The first time I brought it in with this same exact complaint I was given a service bulletin saying it was normal. Weird noise normal? I guess that's the excuse these days. A few years later as my Warranty was running out, "it's the starter." Was hopeful that was it but wasn't. As the Warranty expired, the noise got worse and worse. Turns out to be the Transmission! Oh wow! Finally. What a joke. I'm currently going thru this and have not had the transmission replaced but as an engineer, I knew something was wrong. Let's let them replace the expensive as hell tranny and see if it stops the noise. I feel like GM screwed the engineering up on something and is hoping no one finds out. Glad I'm not them. I hate to explain to my maker how I screwed tons of people some day. F'n BS.
