I have D3's in both my Maxima and Pathfinder. The GPS is unaffected by the reverse wire or Speed sensor wire. That is simply for the 3D feature of the unit. I have it hooked up in my Maxima, but have not bothered with the Pathfinder.
To look up the VSS wire for either pathfinder, simply go to
http://www.avic411.com. Register, and post the question in the forum specifially for VSS wire searching. There are a couple of certified techs, including one that works for Pioneer if I recall correctly. They usually post a response within 48 hours.
PM me if you need the updated discs for the D2.
Hope this helps.Donald