I have a 440 steel crank. I know it's 3.75 stroke, because I measured the half stroke and it's 1.8750. Mains are 440 size. Main seal ridges fall in the direction of a clockwise rotation engine, so I know it's not marine. 6 bolt flange and drilled for manual transmission. Even though I know "what it is" I'd still like to see a casting number "somewhere". I've looked it over pretty good and haven't seen one. I guess it's possible I over looked it. Where are they usually located?