G2 Rear Axle Kits are made from high tensile alloy steels. These axles are forged and heat-treated for maximum strength. Big Spline options allow you to take advantage of even more added strength, gained from the larger diameter of the shafts. The larger diameter enables the shafts to withstand much higher torsional loads than the stock diameter. With either option, you can be assured that the weakest point of your driveline will not be your axle shafts.