I believe only the first gen have the core plugs, but that might also be a first gen/econo only thing.
Someone more knowledgable about them would have to clear that up.

I think the basics are:

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First gen

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2nd gen

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3rd gen

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads