Mine has the fiberglass extensions.
I have a later set of pot metal caps on the shelf to drill for a prop rod for my heavier 70 wing.
My trunk always stays up though without a prop rod, so I still have the fiberglass caps on the car.
It's not like my hinges are rusty or bind, the spring tension is enough to keep the lid up.
To state the obvious, don't prop rod drill a fiberglass cap, the hole will deform with use.