Block casting numbers are pretty much the same as far as Ford's and Merc's go. They are also generic meaning the same casting number can be found on many different bore blocks. So they are not really the best way to ID a block. Granted there are some block numbers paticular to certain blocks. But for the most part very hard to tell what's what from the outside. Head, intake etc....casting numbers are pretty good and can pretty much ID from them. On the blocks you can look for the foundry logos ex: DIF, CF and MCC. Those plus the date code can timeframe the block. But internal inspection will give you the real skinny on things. Some of the 428 blocks can ne ID'd by a sandscratch "A or C" on the back. Even a few 428 PI blocks have a "S". Some earlier blocks like the 390HP, 406 and 63 427 used a "HP" identifier on them that will designate them as hipo blocks. And those HP blocks also have a paticular casting number that applies for the most part. www.428cobrajet.com is another good site to read up on the 428.

G.