"I don't understand how both cranks can be the same part number since they both have a different stroke from the other. Can you post a copy of the parts information your talking about? A 383 is 3.375 stroke and a 400 is 3.380 stroke. Granted it's only .005" different but i don't believe they used the same part number crank for both engines. I will however believe it when you prove it to me."

I don't think you're correct about this. I have always understood that All B cranks share the same stroke and that this stroke is ACTUALLY 3.375, but many application data sheets round up to 3.38"