<P> Starting with the 1974 model year, Rockford would get a new model - year Pontiac Firebird each year throughout the series . The Firebirds used had an identical "copper mist" color with the Esprit's exterior and interior . Although the Firebirds were badged as Esprits, they were actually the higher performance "Formula" model without the twin scoop hood . Garner needed Rockford's car to look like the lower tiered "Esprit" model, a car Rockford could afford, but have the performance necessary for the chase sequences in the show . To achieve this, the show featured Pontiac Firebird Formula's re-badged and re-hooded to look like the "Esprit" model . The "Formula" model was developed to provide the performance of the top level "Trans Am" in a less ostentatious form . Formulas didn't have the Shaker hood scoop, side vents, graphics or lettering used on the Trans Am, but they had the same higher horsepower engines and drive trains, larger front and rear anti-roll bars, stiffer springs and shocks, and a twin scoop hood . (Sharp - eyed car connoisseurs can spot the twin exhausts and rear anti-roll bar on the cars used on the show, options that were not part of the "Esprit" package, as well as spot the different model year cars used in various chase scenes that differed from those in an actual episode, especially in later seasons). Although the series ran until early 1980, no Firebird was used past the 1978 model year as Garner reportedly was displeased with the restyled front end of the 1979 and later Firebird models and as such did not wish them featured on the show (although an answering machine message in one episode in the final season indicated his car was 1979 Firebird). </P> <P> Joseph "Rocky" Rockford drove a GMC Sierra Classic pickup truck throughout the series . The truck had a 400 - inch engine, Turbo 400 automatic transmission, and a 4 - wheel drive factory setup . The custom exterior paint was silver with maroon panels and orange pinstriping . Additionally, the truck sported various after - market accessories added by noted California customizer and off - road racer, Vic Hickey, including the winch, brush guard, hubcap covers, sidestep bed plates, auxiliary gas tanks, custom steering wheel, rear roll bar, Cibié headlamps mounted on the front bumper / rear roll bar, and Pace CB radio . </P> <P> The show's theme song entitled "The Rockford Files" was written by noted theme music composers, Mike Post and Pete Carpenter . It appears at the opening and ending of each episode with different arrangements . Throughout the show's tenure, the theme song went through numerous evolutions with later versions containing a distinct electric guitar - based bridge section . </P> <P> The theme song was released as a single and spent two weeks at No. 10 on the Billboard Hot 100, in August of 1975 . The B - side track (or "flip - side") titled "Dixie Lullabye" was also composed by Post and Carpenter . The single remained on the chart for 16 weeks and won a 1975 Grammy Award for Best Instrumental Arrangement . </P>

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