Just put a D2 in my '04 SD diesel. The dash is different from the '05 so I can't help you there. I didn't install the reverse wire, b/c I am not using a camera and the D2 has been working fine for the past 3mo (just something to consider).
The VSS is Gry/Blk in the harness going to the ABS module. The ABS module is in the front left of the engine compartment just ahead of and below the battery; it has a number of aluminum brake lines going to it. I had to remove the airbox, battery, and battery tray (in that order) to get a good shot at the harness. Open the harness (carefully) and