block casting #'s decoding HELP

I am sure that is 2536430 ?

Anyway I don't think that they cast the 6 pack blocks any different than a standard 440 block, I could be wrong. So a six pack designation, if there is such a thing would be stamped on the block and not cast into it.

http://www.yearone.com/updatedsinglepages/id_info/mopar/mopar casting numbers/castingnumbers.html
and
http://www.yearone.com/updatedsinglepages/id_info/mopar/mopar engine ID/engineinfo1.html