I have a freshly machined never been ran small block chevy 400. The 400 is a 509 casting number 2 bolt main which does have ARP studs for the mains. The block has been baked and blasted to clean it up, mag for cracks, mains checked to spec, notched to clear a 3.875 stroke crank, decked to a 9.005 deck, and has been torque plate honed to final size. There has been a sleeve installed in number 6 cylinder due to a hair line crack. The block also has hardened cam bearings installed along with brass freeze plugs. I do not have the paper work on it but guarantee to be a solid block. If you have any questions call or txt 1 812 . Ask for Erik. Thanks!