.

Casting NumberCIDYearIDNotes

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381917425'65A1st year, big cars.

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386525425'65A1st year, big cars.

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389298400'65B442 only, one year only.

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389244425'66 - '67DBig-car engine. Toro is different internally.

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390925400'66 - '67E442 engine [VERY rare].

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396021455'68 - '70FCommon big block. Stick type F (sans serif).

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396021455'70 - '72F Common big block. Serif type F. Two vertical and a base serif.

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396021455'72 - '76FaVery common big block. Marine also (L VIN derivative).

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396026400'68 - '69G442/Vista/etc. engine.

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231788 455'76LMotorhome, marine and irrigation. GM made motorhomes from '73-8, maybe in all? Casting number appears as "231 [tiny 'L'] 788" on the block.