The only kits I've seen for Navigators are ones that already have factory navigation. The radio bezel surround is different with factory navigation, the opening is bigger. You could try one of those kits and just trim some more of your bezel opening, or buy a whole new radio bezel = $$$$
Thanks for the help guys. Unfortunately, the OEM Navigator navigation bezel is nearly impossible to find. I'm most probably going to have someone fiberglass and paint it for me, as I have no skill with fiberglassing.