What I CAN tell you is that 67-70 Mustang/Cougar, 66-69 Fairlane/Cyclone, 71-73 Mustang/Cougar, and 60-64 Ford/Mercury cars measured 54" flange to flange. As far as which ones precisely were 9"... thats something I can't tell you.
i recently found numerous #'s of 9"s out in the local salvage yard ranging from old f100's f150s to older 70s cars and havent really been able to find a place online or in a book that talks about those years, from what i understand. , Ive been looking to locate one so when the 8" does break and i know it will ill have one ready.