i just picked up a used d3. it only came with the west coast nav disc, and i need the east coast nav disc. i see nav discs for sale all over ebay, but im curious, do i need the an OEM copy of the red east coast nav disc, or can i just run the green ones that say cndv-80mt on them that are like $15. the only thing throwing me is that its an "update disc", and im not really sure if its meant to update the system or if its a replacement to the red one. thanks.