Starting in 1972, and continuing until 1977, the Firebird was only produced at the Norwood, Ohio, facility. Actual production cars yielded 1/4 mile results in the high 14 to 15 second/98 MPH range – results that are consistent with a 3,850 pound car (plus driver) and the engine equipped with a 4-barrel Rochester Quadrajet carburetor rated at a maximum power of 290 bhp (294 PS; 216 kW) at 4000 rpm and a maximum torque of 395 lb-ft (536 Nm) at 3600 rpm figure.
In 1973 and 1974, a special version of the 455, called the Super Duty 455 (SD-455), was offered. The SD-455 consisted of a strengthened cylinder block that included four-bolt main bearings and added material in various locations for improved strength. Original plans called for a forged crankshaft, although actual production SD455s received nodular iron crankshafts with minor enhancements. Forged rods and forged aluminum pistons were specified, as were unique high-flow cylinder heads.
Source: Wikipedia (original)