The Firebird was designed from the Camaro’s F-Body design and the GTO’s A-Body drivetrain with a different rear end, split-grill front end, six vertical louvers on the front of the rear quarter panels, and louver style tail lamps. Improvements were also made in the engine placement, reinforced rear springs, and straddle mounted shock absorbers.
In 1969, extensive exterior changes along with a new interior were made to both the convertible and coupe. They were now longer, wider, and heavier with a new one-piece Lexan front bumper-grill. Additional changes included: theft prevention steering column ignition and steering gearshift interlock, variable ratio power steering unit, single piston caliper optional disk brakes, The optional Koni shocks and the optional wire wheel covers were discontinued during the model year. The optional head rests became standard equipment during this model year. Under the hood, the 250 cubic inch overhead-cam six-cylinder, the 350 cubic inch two-barrel V-8, the regular 400, and the 400 HO (Ram Air III) were basically unchanged. The 350 HO was upgraded to 325 horsepower. A 400 Ram Air IV with 345 horsepower was introduced. In March, the Trans AM was introduced as an optional (WS4) Cameo White convertible or coupe package. It had a 400 HO engine, three-speed manual transmission, improved suspension and steering. The 400 Ram Air IV engine with a four-speed manual or Turbo Hydramatic transmission was optional. The exterior had front fender air extractors, dual hood-roof-deck stripes, blacked-out grille and a rear deck spoiler. The interior had a three-spoke wood-grain steering wheel.
source:first gen firebird.org