This 1973 Pontiac Firebird Trans-Am was built by Gary Hagar at Hack Shack Inc in Rogers, Arkansas. The car rides on a Roadster Shop FAST TRACK chassis with full independent suspension, Penske RS adjustable coilovers, and Baer Extreme 14-inch rotors with six-piston calipers. Under the functional shaker hood sits a 7.0 L LS7 V8 built by Mast Motorsports that makes 685 horsepower and 580 lb-ft of torque. The engine features Mast Black Label 305 cc heads, Mast 3-Bolt Core custom ground camshaft, Callies crank, Callies H-beam rods, and Diamond 2618 pistons. The transmission is a Tremec T56 six-speed manual connected to a Dutchman Motorsports 9-inch independent housing with LSD and 3.73 gears. You can read more about the Firebird and see more photos at Hot Rod.
Source: Hack Shack Inc (build page) and Hot Rod
Be still my pounding heart.