That would apply to several General Motors makes and models of the 1975 model year (first available in September 1974):
"When Federal Motor Vehicle Safety Standard 108 was amended in 1974 to permit rectangular headlamps, these were placed in horizontally arrayed or vertically stacked pairs. By 1979, the majority of new cars in the US market were equipped with rectangular lamps." -from
https://en.wikipedia.org/wiki/Headlamp
"The Buick Skyhawk is a subcompact, four passenger, hatchback automobile that was introduced September 1974, and produced for the 1975 through 1980 model years... ...The Skyhawk, Chevrolet Monza, and Oldsmobile Starfire were among the first vehicles to adopt the newly approved quad rectangular headlamps." -from
https://en.wikipedia.org/wiki/Buick_Skyhawk
"1975 Cadillac Calais models. In front, the Calais Coupe in Jennifer Blue with optional White padded vinyl roof, and in the rear, the Calais Sedan in Commodore Blue. Note the new rectangular headlamps and restyled slim wrap-around parking, side marker, and cornering light assembly." -from
http://automotivemileposts.com/cadillac/prod1975cadi.html
[Pontiac] "1975-... ... rectangular headlights are introduced on Bonneville and Grand Ville" -from
http://www.pontiacheaven.org/Pontiac_History.html
Ford, Chrysler, and AMC (the other three American manufacturers of the time) introduced rectangular headlines to their models over the next few years, but in 1975 selected models of GM's Buick, Chevrolet, Cadillac, Oldsmobile and Pontiac divisions were the first.
