Nobody, repeat...NOBODY changes specs on a mass-produced component with unique engineering specifications for 3rd-party outsourcing without corresponding documentation, including version subsets.
That stated, draw your own conclusions on why GM/Delphi did.
Gee...I wonder if it was ‘2 rogue engineers in the Chicago engineering dept.’...
/s
It’s my understanding they tried to kill this in the bankruptcy, but I’m too busy to follow with detail...
All things being equal, I bet GM would be glad to be called embarrassingly sloppy -- but I suspect that wasn't the truth.
My understanding is the “new” GM was supposedly absolved from taking on the debts of the “old” GM.
However, any known flaws or defects were supposed to be declared to the bankruptcy court and supposedly this wasn’t.