As you've likely heard, Dynacorn is working on a complete '67 Mustang body, which explains why the '67-'68 cowl panels are available before '65-'66. According to National Parts Depot and confirmed ...

The '67-'68 Mustang fastback ... Jay chose the cowl hood, which features a billet grille near the base of the windshield. He likes to say the '65-'66 hardtop has sharper lines than the '67 ...