Has anyone ever found a factory mistake?

[Jack_Tar]

I was talking to the Guy that was painting the outside of my shop office today and he told me of a friend of his that bought a 1968 Impala 396 new. After driving the tires off of it for a few years he had to rebuild the motor. Turned out to be a 427. Being the original owner, he bought and the car was badged as a 396 but would out run every thing around. Now we know why. Has anyone heard of this sort of thing before?