I've looked for quite a while to find a decent GPS for the D3 and have found one.
The unit is branded Masten and is sold by Dig Options out of Melbourne. I have no affiliation with this company. A Google search should find it.
It doesn't fit flush inside the cubby hole but can sit quite neatly there. On/off button is easy to get to and has a AVIN port which my rear wired camera worked well with. You can run a wireless cam if you wish. It has a neat interface and easy to replace the supplied navione app with IGO.
It comes with on road and off road maps but you need to licence the trial version of oziexplorer if you want to use it effectively. Comes loaded with dash command as well for odb2 interface.
It seems to have a great and beefed up GPS receiver which acquires very quickly. This is often the downfall of the cheap Chinese units.