The only parts that I ever saw were floor and trunk pans and most were only listed for Chevy's and that was years ago.
They hadn't quite gotten there but were getting into the devolving process as MBAs instead of engineers began running the car companies. Same thing happened later @ Boeing & in healthcare wrt docs.
I recently found out that all 1973-77 A body's doors are the same, even between the different divisions. Just the skins are different. It probably doesn't help you, but I thought it was interesting. After I read that, I wondered why if they can make the doors the same, why they couldn't they have made the hood hinges the same? They're different between model years and divisions.
actually i think all a body doors where the same minus the skin lol. A body meant the same cab structure so the inside of the door structure for the most part had to be the same. The 76-77 regal and cutlass though had the exact same door.
I mean they where before 73 as well and after. in reality gm had platforms and they started with the same cab to start. Then added unique panels to them, interior, engines. So if you needed a door structure for a 69 you could use any for a 68-72 of any make and weld the proper skin to it. The hinges are different on hoods cause they where different lengths and weights.