I have always had my iPods connect via the dock connector (bottom interface). The advantage of the dock connector is that with one cable you can charge your iPod and play audio. The main source of confusion for most people is that Apple changed the way the dock connector works, so all iPod connection cables are dived into two groups and you have to determine which iPod/iPhone you have and then which cable will work with that device. Currently, I am not aware of any all in one cables for the Becker that work with the iPhone.
When I recently had to upgrade my AUX input when I got my new iPod here is what I did:
I wired a cigarette lighter outlet (like
this ) to the phone connector under the center console. I already had the Becker AUX in (
this ), and then I bought a Griffin Technology AutoPilot.
I plugged the AutoPilot into the lighter socket and the AUX out from that into the Becker cable. It's a clean, simple setup and the beauty of it is that if Apple changes the dock connector again, I can use everything I already have and just upgrade the AutoPilot to something compatible with that new iPod.
I hope this helps!