I was told when I picked it up, 25-30 some odd years ago, that it came out of a dual quad 427 Vette (I took that with a grain of salt because it seemed everybody had those for sale and at the time I really didn't care about the numbers). The guy (very good guy to me) said it was a really good block and crank so I ended up buying it just to have another spare block. Back then I was racing a nitrous fed big block and I think we had a goal of figuring out how much nitrous it would take to break EVERY-THING between the bumpers LOL I got out of heads up drag racing before I "needed" this block and it's been abusing that engine stand ever since.