Noob question here. I just bought an 07 Crewmax SR5 without the JBL system, and am going to upgrade to Nav, either OEM or Eclipse. I added a leather steering wheel with audio & bluetooth controls last night. If I go the OEM upgrade route, I'm wanting to know what the JBL "upgrade" harness does that I see advertised for the non-JBL Tundras. I know I'll need to add an amp either way, and the mic. My truck already has a backup camera in the tailgate, although it appears the flip-down monitor was taken before I got the truck. Are these items that the upgrade harness addresses? Thanks for any input. I just joined the forum, and really like it. Very informative, and helpful.