To make a long story short my cars a 1999 TL with Navi and due to some modifications to the car I ended up going with a 03 Drivers side Navigation wiring. The 03 has onstar.

Anyways are the 99 Harddrive Navigation units swapable with the DVD units and vise versa? For example can I put a DVD unit into a 99 and it will work or a Harddrive into a 03 and will it work? Are the plugs all the same?

Basically I got the 03 wiring on the car with the Harddrive Navigation unit and everything is working but the voice direction on the navigation. It dims out the music but no voice. Does it have to do with something with the Onstar not being there?