Original paint cars

[csx289]

Such as GM A Body cars, the tub would be painted at Fisher Body and the front clip at GM in some cases (such as 69 GTO's)

[L78M22Rag]

I've found that the hood and trunk typically fade differently than the adjacent fenders or quarters... I thought it might be due to a different guage of steel on those panels causing them to heat from the sun and fade differently? But you're right... could be because they were painted differently.