Nope, there never was one. Our 73s look a little funny from the front with all of that front crossmember showing below the bumper. The 71-72s had a front bumper that carried downward a bit lower and hid most of the 'unmentionables'.
I'm looking into what we can use for a spoiler/air dam on our 73s. Maybe a bumper-mounted airdam like is seen on many Ford full-size trucks. The Ford truck airdam is too wide for our cars, and the one on a Ranger is too narrow. Judy (Cougar Kitty) suggested a Dodge Dakota part, so we'll have to look in to that, along with (shudder) a Toyota Tundra or T-100. Don't worry, we'll come up with something!