The conventional wisdom is that 440-blocks cast after 1974 are nonrebuildable, paper-thin junk. Don't believe a word of it. With an NDT Systems CB110 Sidewinder sonic checker, the walls showed an average thickness of 0.275 inch. Generally a reading of 0.125 and above is acceptable. What's more, the deck thickness was a beefy 0.485. For comparison, we also checked a virgin '62-vintage 413 passenger-car (non-Max) block and discovered the '77 440-block (casting number 400663-440-9) to be thicker in every respect.