Small Block Oil Adaptor Bolt ID

Musclesigns said
Has anyone seen the type bolt at the far right of this pic? Original or something else? The other two look right for 70-71 340s. The odd one has a 3/4” head. Wondering if it might be from a 273 motor?

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The bolt on the far right is the one you need to put TTI headers in an early A body. The other two need modifying.