Heads Up Display

I'm wondering if anyone has ever attempted to install a HUD system in their car that did not have the option. I know that I would have to replace the windshield, as well as the dashboard. I want to know if anyone has found if the wiring is there, just not being used or if there is a port for the wiring harness to plug into or if it's just a completely different harness altogether.

My wife loves her Rendezvous, but would really like to have the HUD (we have it in my Park Avenue and she definitely likes it). She doesn't want to get a different Rendezvous just to get the HUD, though. Our Rendezvous has been very reliable so far and we don't want to get rid of it at this point.