Only the SS or optional gauge package. Otherwise they have the rectangular speedometer head and all idiot lights. However the entire gauge style dash interchanges with Monte so that is why I am thinking you are right, it's not Chevelle.
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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)