rear window defogger vents and blower for '67 Barracuda

Dave, you always come thru. My Barracuda is a Notchback. I see where the long thin vent mounts on a Charger, and I suspect it will mount the same on the Fastback, but I anticipated it would take two air diverters similar to the ones in front to move the air. Just can't see how it will mount, unless it is to one of the speaker mount areas. Any idea of where to locate one?