If nobody else can answer I can send you contact info for my friend in Nebraska who has the Don Gay 62 SD. I can't recall, I don't think he had to do the seats but he likely knows if someone has the correct stuff.
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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 (now converted to a "factory" 4 speed)
does anyone know if there is someone making correct apollstry for the 62 sd cars?
if it is the cloth interior it's not available. However I maybe can locate the original cloth so that you can have your local upholester recreate the seats. To start I would need a sample or he original Detroit cloth # or email a picture