I have a 1999 lexus gs 400 withfactory navigation. Iwant to replace it with a pioneer Avic-8200nex. Everywhere I went(best buy, pc richards and a few smaller stores that do free installation) says it cant be done. They saying a custom shop has to rewire the whole car. I just want to replace the head unit, I do not want to bypass the factory amp if my car has one(if it does where is it located)? I cant imagine it being so hard because lexus makes models without navigation. The reasons why im replacing it is I went because to the dealer to buy a new navigation disc(couldn't find it on ebay) because its old. They told me only this particular year doesn't have a disc, it has a hard drive located in the trunk 975 dollars to replace and I would have to leave my car for 2 days to be serviced (no loaner). Then a few months later when I start my car the screen is very faded, if it isnt black for approximately 45 mins. I cant chande the station or heat, navigate until then. I went back to the dealer, they say they know the issue it is happen to a lot of these models that are still on the road. They say the car is it old for a radio recall,bring it in they will swap out the radio for 1300 dollars and keep mine and repair it for the next person coming in with that issue. I refuse to pay that price,so imdoing research on how to do it myself. So this is what ive done so far,I pulled out my radio and seen it has seven plugs on the back. I purchased a climate control from the junkyard, it had the plugs still attached. So i know which two plugs are for that, same amount of wires, same colors in the same locations. Then i purchased Metras 95-8152 and 70-1761 from Crutchfield, it looks like its going to cover the opening with the climate control which fitted in there perfectly. So now my issue is the remaining 5 plugs of which 2 are(the 70-1761) there is 4 wgite plugs and one blue plug. So i figure 2 of those 4 will be for the radio since thats what Metras 70-1761 has. But looking on the back of what seems to be radio controls there is 3 white plugs. So there is one extra plug there,unless it takes three plugs and make it into two. Now the two other plugs, the white and blue one im assuming is the cd changer and cassette plugs. Which im told no head units has cd changer controls anymore. Can someone help me out?