Confused about block casting number

[Kw69]

Hey guys,

Ok hopefull to gain some understanding here on my truck engine. It's a 69 and has the casting of that year of 3956618. In the past my research stated that it was used for 1 year only and only cast for a few months. It's the same block casting of the 302, 327 or 350 of the 69 engines. So again forgive me I'm just trying to understand because I ran into a guy today that had a 302 1969 z28 with the same casting number. So in speaking with him, I was told that this was a rarer block because of the casting and had a high nickel content. I know the internals were different with the 302,327 and 350, but was anything different about the bare block itself? His is a DZ designation and of course mine is not being a general 350 and not a 302. Again forgive me I just don't know, at 44 I'm always learning and enjoy doing so. I p,an to rebuild this engine in the spring and reinstall it back into the truck and use the current crate 350 in another upcoming project. Thanks

[Steeveedee]

My memory says that the Z28 blocks were higher in tin content. I could be wrong, as that memory is over 45 years old. I last worked at a Chevrolet dealer in '72, just before joining the US Navy.

[panhead59]

Casting # 3956618 = 327, 68-69, passenger, chevelle, camaro, nova, large journal
302, 69, camaro Z/28, early '69, 4 bolt maim
350, 69, corvette, 300, 350 hp, 4 bolt main
350, 69-74, pass, chevelle camaro nova monte carlo
350, 69-76, truck
This is the info I have coming from "Cars and parts Catalog of Chevy V-8 Engine Casting Numbers 1955-93 and stamped numbers". Published by Amos press inc. This is a great book identifying engines, crankshafts, heads, exh and intake manifolds, carbs, fuel and water pumps, generator, starters, distributors.

[Kw69]

Wow sounds like a book that I will pick up, thanks for the info.
Kris