The difference in how the scoop opening and how it was finished came up recently and thought I should share the differences and pictures here also
On the early version the corners are much thinner and the surface of the hood extends slightly further towards the rear of the hood. This appear to hand trimmed
The later version had thicker corners and the edge around the opening a bit more rounded.
Since allot of hoods have been replaced and swapped over the years its difficult to determine when exactly the change took place. Plus not allot of documentation of this specific detail
Based on what I'm seeing currently the change may have taken place in the general 6S900-1100 range