ACRS-equipped Impalas featured a modified instrument panel from an Oldsmobile 88. The passenger side airbag was a "dual-stage" unit that used impact sensors in order to determine the amount of force to use when deploying the airbag, based on the severity of the impact. All ACRS-equipped Impalas featured a unique green exterior paint scheme, and had a reinforced chassis from the police-spec Impala, as well as a 350 cubic inch (5.7 liter) V8 Chevrolet small-block engine from the Chevrolet Corvette (C3). All examples of these Impalas were sold directly to fleet buyers, and were not sold to the general public. While General Motors featured a version of the Air Cushion Restraint System in certain Buick, Cadillac, and Oldsmobile vehicles manufactured in the 1970s, Chevrolet would not begin to equip their vehicles with airbags until approximately 1990. One of the examples of an ACRS-equipped 1973 Impala was used on the television sitcom Seinfeld, where it was driven by Cosmo Kramer (played by Michael Richards) in several episodes. Only one example of the ACRS-equipped 1973 Impala is known to still exist, and is owned by an automotive safety expert from Maryland. 1974 For 1974, the rear bumper of Impalas and other full-sized Chevrolets incorporated shock absorbing cylinders to meet the upgraded bumper standards with new taillights above the bumper, separated by the license plate and fuel filler. The front end featured a new grille and headlight bezels, a new header panel, and a bumper with a drop down center section. The marker lights moved back up beside the headlamps. A limited-edition Spirit of America package was offered in 1974 on Sport Coupe models; primarily an appearance package, it featured white body paint, a white full vinyl top, white upholstery with red or blue trim, color-keyed seat belts and floormats, special wheel covers, optional white rally wheels, sports-styled dual remote outside rear view mirrors, a vinyl body side molding insert, and red pin-striping. Special fender and dashboard badges announced the package to passers-by and passengers. This was the only year of the 1971–1976 models the Impala had a different front end design than the Caprice Classic, as other years used either a grille insert or previous year Caprice front to distinguish the two. The rooflines of the Impala coupes were revised. For 1974 the Custom Coupe was no longer a hardtop, with large fixed rear quarter glass and a thick B-pillar. The Sport