Over the years, I've noticed that some bodies, (HQ-Z & WB) have a pair of unused holes in the plenum, one either side of the wiper access grille, under the bonnet seal rubber strip.
Usually this hole had a piece of black tape covering it from new.
Anyone know what this hole might have been for, or why some bodies have it & some don't? Differing build plant?

Not of great importance, but just wondering if there was a reasonable thought why the hole was put there

Cheers
Max