CN 481x block serial number location

Hi All--

I am looking at buying a "lightly used" CN 481x long block setup. I'm hoping to run the serial number by the folks at Chuck Nuytten before spending the money. The seller can't find the block serial number on the block: he is thinking it may be on the bottom of the block near one of the main caps. Of course, the oil pan is in place so that is a small issue.

Can anyone verify where we might look for the 481x serial number?

Thanks in advance.