The Eagle 442541256100 crankshaft is engineered as a replacement for GM LS9 engines that uniquely use a 9-bolt rear flange, a small diameter 58x reluctor, and a long snout for dry sump function. No more need to rig up LS2-style crankshaft sensor for different reluctor wheels. The 4.125-inch stroke is perfect for big-block like displacement and increasing performance. Manufactured using ASME-certified 4340 non-twist steel that has been nitrided and QPAC micro-polished for a superior finish and wear resistance. Designed with a target bob weight of +/- 2 percent to reduce balancing time and often takes no extra heavy metal when combined with Eagle connecting rods and forged pistons.