They list an 8.7 for the Granada on RockAuto's web site. It uses the same pinion bearings and seals. Don't know what gears are like though.
If you look at the pictures on my web page you will see an 8.8 out of a late model Mustang. Might help you for comparison.
Notice the center section is cast, the axle tubes are pressed in then fixing plugs go through from the inside and are welded on the outside.

HTH,

 

i know for a fact its not one of those. the 8" and 9" came with the removable 3rd member. this is like the 8.8" and GM rearends

the manufacture date is 03/77

 

From what I have seen in the junk yard, inline six Granadas had 8" rears and the 302 cars had 7.5 spicers with the cover on the back.
Some six cylinder Monarchs had 9" rears.

It is not an 8.8