You've opened the proverbial can now
I'll start, Pontiac bore spacing = 4.62 Duke bore spacing = 4.25 (appr it's metric).
Did I mention there was some debate on this topic?
While the origins are really moot to me (except for parts interchange), as a Pontiac guy I've always referred to the Duke as a Poncho, but Sirrotica has already made the compelling argument on this. The 153 predates the 301 considerably and it's hard to argue when you look at 'em side by side.
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68 Tempest Conv
06 GTO SRM A4
462 Ram Air VI-LXXI motor in progress
