| YEAR |
CID |
BLOCK NUMBER |
| 1955 |
287 CID |
#158037 |
| 1956 |
316 CID |
#521560 |
| 1957 |
347 CID |
#523293 |
| 1958 |
370 CID |
#528456 |
| 1959 |
389 CID |
#532000 |
| 1960 |
389 CID |
#536387 |
| 1961 |
389 CID |
#538181 |
| 1961 |
421 SD |
#538181 |
| 1962 |
389 CID |
#538181 |
| 1962 |
389 CID |
#542426(SR) |
| 1962 |
421 SD |
#538181 |
| 1963 |
326 CID |
#538211 |
| 1963 |
389 CID |
#543680 |
| 1963 |
421 CID |
#544988 |
| 1964 |
326 CID |
#9773153 |
| 1964 |
389 CID |
#9773155 |
| 1964 |
421 CID |
#9773157 |
| 1965 |
326 CID |
#9778840 |
| 1965 |
389 CID |
#9778789 |
| 1965 |
421 CID |
#9778791 |
| 1966 |
326 CID |
#9778840 |
| 1966 |
389 CID |
#9778789 |
| 1966 |
421 CID |
#9778791(EARLY) |
| 1966 |
421 CID |
#9782611(LATE) |
| 1967 |
326 CID |
#9786339 |
| 1967 |
400 CID |
#9786133 |
| 1967 |
428 CID |
#9786135 |
| 1968 |
350 CID |
#9790079 |
| 1968 |
400 CID |
#9790071 |
| 1968 |
400 RA |
#9792506 |
| 1967 |
428 CID |
#9792968 |
| 1969 |
350 CID |
#9790079 |
| 1969 |
400 CID |
#9790071 |
| 1969 |
400 RA IV |
#9792506 |
| 1969 |
428 CID |
#9792968 |
| 1969 |
303 CID |
#546313 |
| 1969 |
400 RA V |
#9792968 |
| 1969 |
428 RA V |
#545887 |
| 1970 |
350 CID |
#9799916 |
| 1970 |
400 CID |
#9799914 |
| 1970 |
400 RA III |
#9799914(4-BOLT) |
| 1970 |
400 RA IV |
#979991(5)(4-BOLT) |
| 1970 |
400 RA V |
#481708(4-BOLT) |
| 1970 |
455 CID |
#9799140 |
| 1971 |
350 CID |
#481990 |
| 1971 |
400 CID |
#481988 |
| 1971 |
455 HO |
#483677 |
| 1971 |
455 CID |
#485428(LATE HO) |
| 1972 |
350 CID |
#481990 |
| 1972 |
400 CID |
#481988 |
| 1972 |
455 CID |
#485428 |
| 1972 |
366 CID |
#(485)212 |
| 1973 |
350 CID |
#488966 |
| 1973 |
400 CID |
#481988 |
| 1973 |
455 CID |
#485428 |
| 1973 |
455 CID |
#(490)132 |
| 1974 |
350 CID |
#488986 |
| 1974 |
400 CID |
#481988 |
| 1974 |
455 CID |
#485428 |
| 1974 |
455 SD |
#(490)132 |
| 1975 |
350 CID |
#488986(EARLY) |
| 1975 |
350 CID |
#500810(LATE) |
| 1975 |
400 CID |
#488988(EARLY) |
| 1975 |
400 CID |
#500557(LATE) |
| 1975 |
455 CID |
#500813 |
| 1976 |
350 CID |
#500810 |
| 1976 |
400 CID |
#500557 |
| 1976 |
455 CID |
#500813 |
| 1977 |
400 CID |
#568557 |
| #9773155 block with a date code of J23=October 2, 1963 |
| #9782611 block with a date code of F126=June 12, 1966 |
| #485428 block with a date code of D083=April 8, 1973 |
| All pre 1970 blocks have 2 motor mount bolt holts on each
side. All blocks produced after 1970 have 3 holes plus the early 2 bolt set up. 5 all together. The 5 hole blocks will fit the pre
70 chassis. Late in 1977 Pontiac produce 400 blocks with only 3 motor mount holes. All 455 blocks have a 5 hole pattern and will
fit pre 70 chassis. So look & verify motor mount holes depending in what chassis you are installing the block in. |
| 400 Blocks produced after 1975 with the last 3 numbers
#557 have an undercut support area from the main to the pan rail & I don't recommend for 400hp plus builds. |
| All year 455 blocks will take 500hp plus with the proper
prep work |
