| Years | CID | Casting Number: | Notes: | ||||
| 1955 | 287 | 518037 | |||||
| 1956 | 316 | 521560 | |||||
| 1957 | 347 | 523293 | |||||
| 1958 | 370 | 528456 | |||||
| 1959 | 389 | 532000 | |||||
| 1960 | 389 | 536387 | |||||
| 1961 | 389 | 538181 | |||||
| 1961 | 421 SD | 538181 | no transfer lug | ||||
| 1962 | 389 | 538181 | |||||
| 1962 | 389 | 542426 | Stock Replacement | ||||
| 1962 | 421 SD | 538181 | no transfer lug | ||||
| 1963 | 326 | 538211 | |||||
| 1963 | 389 | 543680 | |||||
| 1963 | 421 | 544988 | |||||
| 1964 | 326 | 9773153 | |||||
| 1964 | 389 | 9773155 | |||||
| 1964 | 421 | 9773157 | |||||
| 1965 | 326 | 9778840 | |||||
| 1965 | 389 | 9778789 | |||||
| 1965 | 421 | 9778791 | |||||
| 1966 | 326 | 9778840 | |||||
| 1966 | 389 | 9778789 | |||||
| 1966 | 421 | 9778791 | Early Year | ||||
| 1966 | 421 | 9772611 | Late Year | ||||
| 1967 | 326 | 9786339 | |||||
| 1967 | 400 | 9786133 | |||||
| 1967 | 428 | 9786135 | 4 bolt main | ||||
| 1968 | 350 | 9790079 | |||||
| 1968 | 400 | 9790071 | |||||
| 1968 | 400 | 9792506 | Ram Air 4 bolt | ||||
| 1968 | 428 | 9792968 | 4 bolt main | ||||
| 1969 | 350 | 9790079 | |||||
| 1969 | 400 | 9790071 | |||||
| 1969 | 400 | 9792506 | Ram Air IV 4 bolt main | ||||
| 1969 | 428 | 9792968 | |||||
| 1969 | 303 | 546313 | |||||
| 1969 | 400 | 9792968 | Ram Air V 4 bolt main | ||||
| 1969 | 428 | 545887 | Ram Air V 4 bolt main | ||||
| 1970 | 350 | 9799916 | |||||
| 1970 | 400 | 9799914 | |||||
| 1970 | 400 | 9799914 | Ram Air III ( 4 bolt) | ||||
| 1970 | 400 | 979991 or 9799915 | Ram Air IV (4 bolt) | ||||
| 1970 | 400 | 481708 | 4 bolt main | ||||
| 1970 | 455 | 9799140 | |||||
| 1971 | 350 | 481990 | |||||
| 1971 | 400 | 481988 | |||||
| 1971 | 455 | 483677 | HO 4 bolt main | ||||
| 1971 | 455 | 485428 | Late HO | ||||
| 1972 | 350 | 481990 | |||||
| 1972 | 400 | 481988 | |||||
| 1972 | 455 | 485428 | |||||
| 1972 | 366 | (485)212 | |||||
| 1973 | 350 | 488986 | |||||
| 1973 | 400 | 481988 | |||||
| 1973 | 455 | 485428 | |||||
| 1973 | 455 | (490)132 | SD no transfer lug | ||||
| 1974 | 350 | 488986 | |||||
| 1974 | 400 | 488988 | |||||
| 1974 | 455 | 485428 | |||||
| 1974 | 455 | (490)132 | SD | ||||
| 1975 | 350 | 488986 | Early | ||||
| 1975 | 350 | 500810 | Late | ||||
| 1975 | 400 | 481988 | Early | ||||
| 1975 | 400 | 500557 | Late | ||||
| 1975 | 455 | 500813 | |||||
| 1976 | 350 | 500810 | |||||
| 1976 | 400 | 500557 | |||||
| 1976 | 455 | 500813 | |||||
| 1977 | 400 | 568557 | |||||
| 1978 | 400 | 568557 | |||||
| 1979 | 400 | 568557 | |||||
| Notes: | |||||||
| All 421/428/455 blocks have a "TRANSFER LUG" cast into the block near the distributor hole. | |||||||
| 1955-1958 blocks had no side motor mounts, they used a mount under the timing cover | |||||||
| All blocks prior to 1964 had the casting number on the passenger side of the block. | |||||||
| 1964 & up have the casting numbers by the distributor (Except 421's) | |||||||
| 1959 thru 1969 blocks have 2 motor mount holes | |||||||
| 1964 was the start of block mounted starters | |||||||
| Starting in 1965, cylinder head oiling passages were eliminated from the blocks. | |||||||
| 1955 thru 1966 have 2 freeze plugs per side. | |||||||
| All the above information was taken from Pete McCarthy's "Pontiac Musclecar Performance" book. | |||||||
| Date Codes: J23= October 2,1963 D083= April 8, 1973 (or 1963 !!) | |||||||
| The letter is the month, followed by the day (one or 2 digits) and the last number is the year. | |||||||