Dave, those speaker grills are nearly indestructible. I have two kids in the back seat, sometimes hockey bags and sticks, sometimes two big dogs. Not even a scratch on the speaker grilles. It's metal mesh and molded plastic.

In case you want to mount speakers there, be advised that on a '69 convertible there is less than 2" of clearance in that location as the top raises/lowers. If your top NEVER moves, you have more room