Unfortunately, no one has been able to help.
GM - Not surprising you get a GM specific requirement. It's been a long time since I worked with GM or a GM supplier that I simply have no idea. I've even forgotten the requirements they had years ago when I worked with them on their airbags - I remember there were literally - Well, I don't remember how many, but I had a lot of binders with GM specific requirements. At some point in time since they were essentially irrelevant to me I trashed them.
The last time I was active in automotive was probably 10+ years ago. I sort of keep watch, but do not have much reason to these days. I worked with automotive starting back in 1988 through 2004ish. These days it's almost - Well, Customer Specific Requirements.
Then again, these days they're into battery cars and self driving cars. I can understand the increased requirements. Customer Specific Requirements, for example, became much more prescriptive when airbags became "standard". Some of you may remember that GM was late to acceptance of airbags. We must also understand GM's reluctance. In the early days there were quite a few airbag related lawsuits, including by people expecting airbags to be "fail-safe life preservers". I can say this because I was involved in what we now call "restraint systems" from the early days. I'm old and what cars today have are beyond what we conceived of years ago.