Chevy OE cranks, cyl. heads.

[Greg Reimer 7376]

That's absolutely fascinating reading how they did all that. We've all seen parts with the same casting number,say, an #803 intake or #3917290 heads, or #462 heads, and as long as they conformed to the tech info in the classification guide, the rest of the numbers didn't mean much. This does a lot to update info on what the rest of the numbers mean.