ok, i havent already installed one i guess, double din is double din, if you actually check on the chassis size and not the face size, the 8" is the same exact size as a normal double din radio, all you need to do is trim the dash opening... no matter what year the vehicle is you need the aftermarket double din radio install kit to start with cut dash to fit larger face
i havent installed a ipad in a grand cherokee dash either
I think that you need to step back and take a look at what you've written above, relative to double DIN, then take a look at what I wrote in my last post.
Double DIN is always in the 4" x 7"(nominal) configuration so where are you getting the fact of using a Double DIN installation kit as being the solution?
As I noted previously, the '08-'10 uses the MyGig, and the MyGig chassis(NOT face plate, but chassis) is a 3 1/2" x 7 1/8", and it fits very tight, on the top-to-bottom dimension, so that sets the max height, unless you want to start cutting into the dash superstructure, which is not a good idea. But more importantly, it means that the existing installation, that being the MyGig, is not a Double Din configuration, but is smaller on the top-to-bottom dimension.
Moving along, the Alpine INE-Z928HD has a chassis size of 3 3/8" x 7", making it essentially a Double Din configuration, which won't fit into the existing MyGig space, nothing more complicated than that.
And this isn't even tackling the face plate issue, but given the chassis deal, this becomes a moot point.
But, and this is the big one, if you have a pre-'08, then installing an INE-Z928HD is no big deal.