transmission on coupes and sedans, and the big-block 455 was no longer available. The four-barrel 350 V8 became standard on station wagons. A new landau top became available for fastback coupes that partially covered the rear quarter glass, giving an appearance similar to the formal-roof Century Custom. A Century Special coupe was added to the lineup, using the fastback roofline. The Special was marketed as an economy variant of the Century and was only available with the V6 engine. In 1975, the US government legalized rectangular headlights and Buick added them to the Century for the 1976 model year, positioned side-by-side on coupes, and stacked vertically on sedans. Sedans received a taller, more-formal grille, while coupes got an angled, body-colored front end along with new bodyside sheet metal that lacked the traditional "sweepspear". The Gran Sport option was discontinued with the 455 engines and only 231 V6 or 350 V8 were available on the last 1,288 made vehicles merely with appearance and suspension option package. To commemorate the Bicentennial of the United States, the standard colors available on all Buicks were Judicial Black, Liberty White, Pewter Gray, Potomac Blue, Continental Blue, Concord Green, Constitution Green, Mount Vernon Cream, Buckskin Tan, Musket Brown, Boston Red and Independence Red, with specially available colors on select models Congressional Cream, Revere Red, Colonial Yellow and Firecracker Orange. In 1977, the V6 engine was revised to be even-firing, and a Oldsmobile V8 was added as an option for station wagons. Buick Centuries were used in the 1975 and 1976 Indianapolis Motor Speedway as pace cars. Buick introduced a 1975 Buick Century "Free Spirit" edition replica based on the Indy Pace Car for the public with patriotic graphic decals and the Buick Hawk on the hood. This 1975 vehicle had a transmission shifter on the floor with bucket seats and "Hurst Hatch" T-tops installed. The white exterior and blue/white interior were based on the 1975 two-door sheet metal. The engine was a 350 V8, as opposed to the 455 V8 used on the actual Indy 500 Pace Car. Alternatively, in 1976, Buick introduced the "Free Spirit" edition of the Indy Pace Car; it was downsized to the 1976 Special facelift sheet metal with a 231 V6. The original Indy Pace Car had the turbocharged 231 V6. The replica featured a silver, black, and red paint with a black interior. The vehicle included a positive-traction differential. Production