Yay! A Zombie thread!
Those cars have VERY distinctive backends.
The rear window lines definitely put it as an early GMC H-body, most likely a Vega/Astre (later model H-body coupes had a more pointed design), but the front grill is what it is making it difficult to place an exact year/model. It could be an aftermarket grill as whenever it was added, it was long after they stopped making them.
But the previously mentioned video and pics are no longer available