You might have been talking to someone not knowledgeable. I used the ISTY571 and it works perfectly. If you look at their page they show compatability on the "All Applications" tab on the page in the center. It actually lists LS430 2005 and LS430 2006. Us smart people know the 2004 is the same. I put it in a 2004 and it works quite well. No issues, perfect integration. You might use SoundsGreatUSA through Amazon. You don't pay more and you get the Amazon support and warranty and the SoundsGreatUSA smarts for the right parts.

Here is the iSimple page:
http://isimplesolutions.com/bestbuy/...?productid=914

Here's the Amazon link:
http://www.amazon.com/s/ref=nb_sb_no...tusa%20isty571

The Gateway is $63.97 and the iPod interface (Apple type) is $39.99

 

Correction, the iPod interface is a Bluetooth iPod interface. You can save that $40 if you don't need iPod Bluetooth and just spend $64