I was all set to purchase a new nav head unit but I had some house repairs to deal with. I need help hooking up a line output converter in a 2007 Tundra DC with JBL. Where can I gain access to the inputs I need for this? I looked at the Metra 70-8117 harness but I'm not sure its what I need. I do not want to hack any wiring if possible. Any info would be greatly appreciated.