1966 dart commando 4 speed id

chryslerfat said
My 65 commando 4 speed Barracuda is 7 1/4 and 9 inch power brakes including build sheet.

I'm surprised it didn't have 10" brakes. All the V8 cars I've seen that year came with 10's.....even some 6 cyl cars. Is it an early build date?