Can you help ID this stuff THanks.Motor casting #500557 0483261 26P337117 with 6X heads.
X7
trans 8640399 cast into bellhousing ( auto)
CFD
all this came out of a 67 GTO!I think it's mid 70's stuff thanks for you help.

Can you help ID this stuff THanks.Motor casting #500557 0483261 26P337117 with 6X heads.
X7
trans 8640399 cast into bellhousing ( auto)
CFD
all this came out of a 67 GTO!I think it's mid 70's stuff thanks for you help.

'76 Pontiac 400 from the block casting & serial number. The 6X's should be 6X-8's.

The X7 from '76 is one of the missing codes not in Pete's book...

The 557 block is something you should just throw away as the main saddles on those blocks are very thin & Pontiac even stopped using those after a 2 year run because they kept coming back for warr. repair with broken blocks. I wouldn't use that block unless you were doing a 76-77 numbers resto & it would need to be a very low powered engine & you don't run it hard EVER.

MYTH.. :rolleyes::rolleyes::rolleyes::rolleyes:They are good to 350 HP. I have run every '77 W72 engine I owned to redline several times and never blew any of them up. 12 and counting..

They are not good for stroker conversions or high HP builds. For mild to moderate running, they are fine.

I also believe the 557 blocks were produced from mid 1975-1978 including the 1977 W72. The only non 557 blocks built after 1975 were the 1978-79 W72.