I don’t think there is a specific cutoff. Cars were not necessarily built in sequence. Dashes evolved. Seats changed thru the production. Some very early cars had 2 piece seats, as you know the same seats showed up on Panteras. For sure early cars had the lower switches and mid- production got the lower dash A/C vents. 2 headlamps came around the 1060 mark. (From memory) there may have been a couple random as prototype earlier). Rear body gussets were late production improvements. There are a few unique elements on very early cars and late production cars.
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