Time to unwrap the very big fish. The concave rear window is the give-away. But I did lift up the tarp a couple of inches on rear wheel cover, which had a certain reinforcing brand name on it, as if that was necessary. Tata!
1971 -1973 Chevrolet Impala Custom Coupe. The Caprice Coupe shared the same roof-line, but had different wheel covers and rear wheel spats.
Here’s the view of that distinctive concave rear window.