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.
I couldn't find anything either. Picked up an R3 block along with this crank and other parts, But the block has 340 journals. Just trying to figure things out. What the guy had going on .
