It happens that I am a retired GM Engineering Center Director, but I retired exactly a quarter century ago today (as of 1/1/00). All my contacts from that era are also retired by now, and many of the Engineering Centers are gone, too. However, I can likely find a secondary contact in an engineering organization rather than a marketing division who might have worked on this or at least is aware of it. All of the engineering of engines and transmissions was performed in the Powertrain Division at that time, and I believe they still are.
When I visited the corvette plant in Bowling Green, shortly after the sinkhole opened up & swallowed several cars at the museum, I seem to remember something to that affect bring said when we all went through the actual plant. That would have been 2014. So, you are probably correct that it still operates that way. 🙂👍