There used to be repro pieces. The cap is the same as Chevrolet but the ornament is unique. Dale's Musclecar used to have them but I don't see them on his site any more.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
Here are the hubcaps I was talking about. The center caps are in pretty good shape, better than the rest of the hubcap itself.
I bought these from an antique vendor, who was having a going out of business sale and he had the hubcaps mislabelled as Chevy.
Anyway, truth be told, I spent very little on these and won't be asking much for them. If you just want the center caps, I have no problem separating them.