Has anyone ever found a factory mistake?

[RichSchmidt]

Not a factory mistake,but interesting nonetheless.When I first got into the hobby,I pumped gas at a local gas station where the mechaic was a GM dealer mechanic in the mid to late 60's.He was telling me how a customer came in with a 65 vette with a blown up 425hp 396,and service replacemnts for those engines were hard to find,so they threw in a 425 hp 427 and didnt bother to tell him about it.I bet that one made for a zippy combination.