Who here knows 1968 Chevy big cars?

[442w30]

Today I stumbled upon a claim - not the first time - about front side marker overlays being red, and that a running change was made. Today's post said only Canadian 427 cars received this.

I've always had the idea that the red was just the overlay that changed color with age. Is there anything documented that proves that more than one lens was available, like a running change? And what about them being 427-specific? And even for Canada?

Thanks!