I crossed it over to a Wagner BH64995 and Wagner lists that one as being 10 1/2". One thing though, I don't always find Wagner's crossover to be identical to originals.
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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)