I bought a nice 600 dollar 12.1 in display for my 2010 Lexus ES 350 and the wiring harness is not all there. I was posting this to see if I could get some help on tracking a correct one down and input would be much appreciated!

 

I would take the unit and harness to an audio shop guy. Somebody reputable. And just purchase the harness or ask what is needed. If the oem unit is gutted already it would make install for them very easy, and you could just pay a shop to install it. Best Buy is a good option for car audio also for budget stuff, and are very knowledgeable with these kinds of questions. Also you can probably just ask them for free without them trying to sell you on stuff.