Heres a Sonny Bryant 4330M billet crank. The stroke is 3.950" with standard big block Chevy main and rod journals. It has the extra counter weights in the center to help balance the crank at high RPM. Its also gun drilled to save weight. and notice the knife edging on the counter weights. This crank is CNC cut form a 300lb. billet of steel until its about 65lbs. It takes 14 - 16 weeks for them to make it.