I don't think all V8 A bodies had (or were even supposed to have) 10" brakes. My '64 273, 4 speed Barracuda came with 9" x 2" drums all the way around. I've owned it for over 32 years & it was all original when I bought it. I believe all '64s were this way. Every one I've ever seen had 9" brakes. I read in the book "Dodge Challenger & Plymouth Barracuda" by David Newhardt that all '65s with V8s were supposed to have 10" brakes but that some slipped through with the 9" ones. I also noticed some things he was wrong about in the book, so I don't know for sure about what he says about the '65 models. Every 65 or later V8 A body that I've dealt with had 10" brakes.
If the car is a Formula S it really should have 10" brakes all the way around, but easily could have been switched somewhere along the line. Are you sure the brakes are 9"? What you describe sounds like the "flanged" 10" x 1 3/4" drums I currently have on the rear of my car. I have the 8 3/4" rear & brakes from a (71?) Demon.
:burnout:
I mis-spoke in the above post. It wasn't in the Newhardt book where I read that some V8 '65s slipped through with 9" Brakes. I can't figure out where I read it, but I know I did somewhere................... AAAAARRRRRRRGH!!!!! :banghead: It's terrible getting old! They say the mind is the first thing to go......... :tard: