I would say that it's a good possibility that ordering the "Two-Tone Hood" would trigger the "Louvered-Turn Signal Hood". say this only because the 1968 Sales Brochure (not always "Gospel", as we know), notes under Options "Two-Tone Hood (Louvered Hood Required"). Although, one would think that they still should have listed it separately. Or possibly, when the Customer ordered the car, he noted that he wanted the "Two-Tone Hood", and the Salesman either didn't write down the Louvered Hood (or didn't realize that it was required), and when Ford got the order, they "automatically" added the Louvered Hood since it was required with the Two-Tone. Just a thought.
Bob