I agree entirely with Peter. The antenna behind the instrument cluster is the easiest way to go. In fact, that is the antenna system I original purchased for my configuration, until someone mentioned that they had one that could be used for the shark fin.

My first time tackling the unit installation, I used the antenna behind the instrument cluster for testing purposes. It was extremely easy, and one attempt I could not pass up on. Ran with it for a couple of days, until the other wire showed up, and I had to take it apart again to do the trunk wire method.

No rattles either, and it cut down on installation time by a huge amount, as you are already taking the instrument cluster out anyway.