Mark I, II, III, IV, V: The Mark series is the big block engine family starting with the 348 in 1958 and continuing through the current 454 and 502. Mark I included the 348 and 409. Mark II was the NASCAR Mystery Motor 427. Mark III never reached production. Mark IV started with the 396 and included the 366, 396, 402, 427, and 454. Production ended a few years ago on Mark IV. The current 454 and the 502 are part of the Mark V group.

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Big Block Chevrolet: The 366, 396, 402, 427, and 454 Mark IV family of engines. There have been other variations in the aftermarket world and in the Chevrolet special products world of aluminum engines for Can Am and for boat racing but those are expensive and you will rarely see one. The 366 is an old truck engine from the mid '60s and is probably equally rare today, even though many were built. See Rat Motor.