On 65-66 fastbacks, I seem to recall seeing a few original cars where the largest vent screen piece in the rear louvers had the chicken wire painted black. This is the only one that that has the chicken wire attached by bending over the edges of the diecast housing... which makes it nearly impossible to remove without breaking apart.
I don't remember exactly what year/assembly plant cars I saw this on... I think at least one was a '65 San Jose car.
I'm currently working on a Jan '66 Metuchen fastback and this detail had me wondering... I did see signs of black paint on this one, but it could have been something a previous owner did.