The '430 crankshaft from Subaru is their latest and greatest factory EJ crankshaft. The crank is nitride treated to be extremely hard and reduce the chances of wear and damage from foreign material. Through nitriding, surface hardness is doubled on the Rockwell scale, and fatigue life is increased by 25 percent. The dark finish is due to the temp and duration of processing for a deeper hardness. Rebuild your motor using Subaru's finest.