mine is the same as the 03. I went with the basic harness and as far as I can tell, I only lost the chimes...no big deal. I think the guy was just trying to sell me the adapter, which does look pretty cool. I didn't inspect it very well or research it, but it had rca's on it. maybe amp outputs for an included line converter? not sure why if all aftermarket heads have built ins. don't think they could be universal inputs.