Model year 1973 started Corvette's transformation from muscle to touring sports car. A Chevrolet advertisement headlined: "We gave it radials, a quieter ride, guard beams and a nose job." Indeed, redesigned body mounts and radial tires did improve Corvette's ride, and interior sound levels were reduced by 40%. The chrome rear bumper was essentially carried over from the previous year. However, the chrome blade front bumper was dropped for the federally required standard for a light-weight front bumper system with an inner transverse tube attached to the frame with two Omark-bolts-(special steel fasteners which absorbed energy when a forming die, pushed back by the bumper, was forced down their length), and an injection-molded urethane bumper cover. The urethane nose was chosen over Chevy's other alternative, a more protruding version of the previous metal bumper. The new urethane bumper assembly added thirty-five pounds to the front end. Two small block engines were available. The base L-48 engine produced . The L-82 was introduced as the optional high performance small-block engine (replacing the LT-1 engine) and delivered . The new hydraulic lifter motor featured a forged steel crankshaft, running in a four-bolt main block, with special rods, impact extruded pistons, a higher lift camshaft, mated to special heads with larger valves running at a higher 9:1 compression, and included finned aluminum valve covers to help dissipate heat. The L-82 was designed to come on strong at higher RPM and ordered with nearly 20% of the cars at a cost of $299.