Hull construction of GB52 Heritage EU?

[Garrett]

I was curious what the hull construction on the GB52 is and if it has changed through the years:

Is the bottom solid or cored?

I believe the sides are cored -- what material was used for coring? Foam? Balsa? Other?

Has the construction changed in different vintages? I know GB went fully cored in some model somewhere around 2007 -- did they change how the construct the 52 Heritage EU around this time?

thanks,
Garrett