8" was the only rears put in these cars except for the very early 70 which had a 7.5. The 9" was never an option.
You can get a 'bolt in' 9" out of a Granada/Monarch if you so desire. It is 1/2" wider per side, but everything else is identical. So if you don't have huge tires or custom rims with an extremely tight offset, the width is not noticeable. Dave
All of the first generation Granada/Monarchs were available with 7.5", 8", and 9" rears. I want to say 75-81 were the years. I got one from an 81 Monarch in a junkyard. They charged me 80 bux because their computer only showed an 8" as available in Monarchs and that was their flat fee for an 8". The second gen Granadas were Fox platforms and use coil springs out back, and 4 lugs. Dave