This appears to be an Ellis manifold for the "big block" (361 cid and up) GMC. If that is what it is, it will not fit the 228-248-256-270-302 series. In the only photo provided, it resembles an Ellis manifold for the 270-302, but one would have to examine it closely to confirm what it is. It should bear markings that would positively identify it. Failing that, one would need to measure it.
God's Peace to you.
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Inliner #1450
