Crankshaft ID needed

Looking it, is definitely steel. I'm goin out on a limb to say the "FS" probably means forged steel. Beyond that, I don't know. Normally, crankshaft numbers include the type of steel, sometimes the rod length and the stroke. So, maybe the 4000 at the end is 4" stroke? All guesses of course. I searched for a while and found nothing.