removing 64 barracuda dash defrost vents

You will have to get in an uncomfortable position almost standing on your head and reach under the dash and look up there with a flashlight and move the tensioner and pull the hoses off. Then get a socket, it looks like a 5/8 to me on an extension and carefully turn them counterclockwise about three times till they come off. You can certainly do it without taking the dash out. By the way, taking the dash out involves removing the windshield.