Ford Repair: Lincoln Versailles Disc braks rear end, rear rotors, lft

Question
I purchased a 1979 Lincoln Versailles 9" disc brake rear end complete. All information I have found so far shows that there are two rotor sizes either 10" or 11". The rotors on this seam to be stock and they measure an outside diameter of 11.50". Am I measuring wrong or are mine an odd factory size or possibly aftermarket?

Answer
wag bd 60439 and bd 60440 are the part numbers for wagner rear rotors there is only one size rotor-the 9 or 10 inch is talking about the drums.

the rotors have two different part numbers which mean they are directional be sure and look to see which one is right and left.
drivers side is left (as you are sitting in car is what rt and lft is determined by)