It is amazing how vertically integrated GM used to be - for a vehicle they made just about everything except the windshields, the paint, and the tires. They also made city buses, diesel locomotives, fractional HP electric motors, earth moving equipment, consumer kitchen products, and sold insurance. They even had their own university that awarded bachelors and masters degrees. All of that is long gone now.

Also nuclear reactors and the uranium fuel rod assemblies those required.

My distilled belief is the finance guys managed to regain control of things from labor and manufacturing in the early 70's. After 1980 came the complete financialization of the American economy. Instead producing goods, services and jobs companies were pushed to create 'paper'.

That's why GE and GM both let the finance part of the business wag the dog.