BBC oval port cylinder head casting numbers
Number Engine Size Year Combustion Chambers
336781 454 1973-1985 Open chamber
346236 454 1975-1978 Open chamber ("peanut" ports)
353049 454 1970-1973 Open chamber
3872702 396 and 427 1966 Closed chamber
3904390 427 1966 Closed chamber
3904390 427 1966 Closed chamber
3909802 396 and 427 1966-1967 Closed chamber
3917215 396 and 427 1966-1969 Closed chamber
3931063 396 and 427 1966-1969 Closed chamber
3964280 427 and 454 1966-1970 Closed chamber
3964290 427 and 454 1966-1970 Closed chamber
3993820 402 and 454 1970-1971 Open chamber
3999241 402 1970-1972 Open chamber
6272292 402 and 454 1971 Open chamber

BBC rectangular port cylinder head casting numbers
Number Engine Size Year Combustion Chambers
3856208 396 1965 Closed chamber
3904391 396 and 427 1965-1967 Closed chamber
3919840 396 and 427 1965-1969 Closed chamber
3964291 396, 402, and 427 1965-1970 Closed chamber
3964292 454 1970 Closed chamber
3994025 454 1971 Open chamber
3994026 454 1971 Open chamber
3996074 454 1971 Open chamber
6258723 454 1971 Open chamber
6272990 454 1971 Open chamber