I know it's not a 6-pack block. It does not have 318 on it has 340 after the casting number. What I thought was strange is there is no VIN anywhere on it. Plus the numbers on the passenger side below where the cylinder heads goes. They are in picture 3 and are all a mixed up mess. I was just wondering what it was. I have never seen those goofy numbers and one with no VIN. IDK, it was a bare block and the cylinders were standard bore when I got it. It mag and sonic checked good and it's .040 over bore now. It's getting that forged crank and built for something. I don't what yet but I'm glad I bought it! :)