Says the same in the 2004 and 2005 product information. It's referring to the increase from the V-6 CTS.
2004 quote below. 2005 is the same as your quote.
Heavy-Duty Driveline
The CTS-V is equipped with a high-performance prop shaft. Design enhancements include upgraded constant velocity (CV) joints and an increased steel tube diameter of 70 millimeters to contend with the increased rotational speed and higher torque requirements of the CTS-V. The prop shaft is supplied by GKN, an industry leader in the development and manufacture of driveline systems and components. The result is a robust driveline package, offering enhanced noise and vibration characteristics.
The input flange to the rear differential is constructed of thicker gauge steel for enhanced rigidity and strength, ensuring there is no feedback through the driveline. In addition, the rear differential housing – made of cast aluminum – incorporates significantly deeper cooling fins on the bottom (approximately three-inches in length) and a cast-in top grate for additional reinforcement and cooling.
The limited slip rear axle is fitted with a 3.73:1 final drive ratio to optimize acceleration.
2004 quote below. 2005 is the same as your quote.
Heavy-Duty Driveline
The CTS-V is equipped with a high-performance prop shaft. Design enhancements include upgraded constant velocity (CV) joints and an increased steel tube diameter of 70 millimeters to contend with the increased rotational speed and higher torque requirements of the CTS-V. The prop shaft is supplied by GKN, an industry leader in the development and manufacture of driveline systems and components. The result is a robust driveline package, offering enhanced noise and vibration characteristics.
The input flange to the rear differential is constructed of thicker gauge steel for enhanced rigidity and strength, ensuring there is no feedback through the driveline. In addition, the rear differential housing – made of cast aluminum – incorporates significantly deeper cooling fins on the bottom (approximately three-inches in length) and a cast-in top grate for additional reinforcement and cooling.
The limited slip rear axle is fitted with a 3.73:1 final drive ratio to optimize acceleration.