I just replaced my stock stereo and no longer need this.
Blitz iPod adapter. It connects into the back of your stock head unit. I had the non-JBL and it worked great, not sure if it will work with the JBL, or not, but if you have a CD changer port, it should. It just plugs in to that. It takes 5 min to install.
This works AWESOME! I don't know how anyone could own a car without an ipod hooked up to it.
I think I paid $100-$110 new, selling it for $50 shipped.