One sequential number off; I would call that numbers matching. They were hand stamped so some one picked up the wrong die set off the bench were they were stamped, or not paying attention to the sequence when assembling the dies in the fixture before smacking it with a big mallet.
But then I don't make the call, some judge in a car show does.
Big blocks were stamped going back to the 409 motors that were in the '63 model year. Also fuel injected SBC models or any motor that was factory rated above 300 basically (because they were prone to theft).
Please Visit our new site: http://www.winvoices.com/
1959 through 1988* window stickers, car shippers, dealer invoices, retail sales orders and tank stickers, expertly reproduced, for most Chevrolet Models.