Well, you can shorten the housing of the 69 or get custom axles for it that are longer than a 65. Not sure but maybe the 65 axles will fit a granada rear, even though 65 stangs is 3/4" shorter over all than the granada.
Why don't you try the Mustang II 8" rearend? They are abundant. What is funny, is that the II guys are always trying to steal the 65 rearend because the track is so close and it has five lugs. Since you already have the axles, you can simply remove the four lug axles and bolt your old axles back in. You will need to reuse the old bearing retainer however.
That's a good idea, but this one isn't for me. I've got a 9 inch in my car. But was curious about getting rid of some of my plethera of extra parts lol. Thanks guys!
--Shaun