Marvin opted for the No. 10027 4340 steel crankshaft from Probe Industries along with 6.250-inch 4340 H-beam rods (No. 10082). Because the N351 block calls for a smaller 2.750-inch main journal, we're going with a 351C crankshaft, which has this main journal size. And this is the main journal size you want with the N351 block.