A Granada w/rear discs? I didn't think there was such a thing. Are you sure you don't have a Lincoln unit?
For a cheap gear swap in a passenger car 9", look for the pumpkin from a F-100 pickup with the gears you are looking for. IIRC, they are 28 spline like the passenger car nine inch rears, and can be swapped.
It's an okay unit (less splines, smaller bearings, weaker housing, etc.) compared to the F-150 models or the aftermarket high zoot stuff.
I ran a Mustang 9" in a 5.0 converted Bronco II on 32s and it held up a heck of a lot better than the factory Ford 7.5 pos ever did. I got it free, and free is my price so I ran it.
What are you trying to accomplish with a rear end swap?