Hmmm,
David, maybe California cars were all assembled in the old Southgate plant, or even Freemont. Plagued with extra California emission controls as well.
Now Oldsmobile having less market share did not need a second or third plant to meet demand, so all Cutlasses came from Lansing with uniform quality, and back in those days, an Olds, or a Buick was know for better quality than a Chevy or a Pontiac.
GM was a huge operation with nine domestic assembly plants for A and B body cars.
Besides Los Angeles, Freemont, and Michigan, there was a plant in Atlanta Ga., Arlington Texas, they still build trucks, Fairax Kansas, Oklahoma City, Wentzville Mo., Lordstown Ohio before the Vega, Framingham Mass., Linden NJ, Baltimore Md., and Wilmington Delaware.
F bodies were built either in Norwalk Ohio, or Van Nuys Ca. Willow Run, Mi. built Nova's, and the Buick Apollo/Skylark, and Olds Omega.