Hi! I'm considering to buy an ES 350 2008 navigation equipped (no Mark Levinson) with 40k miles (almost new). The problem is the outdated stereo/hvac system and I want to upgrade it by an aftermarket one. I read that to convert the navigation system to a head unit like an Alpine double din is really tricky, but few double din conversion kits are available if the car is equipped with the standard unit (without navi). So my question is: Is it possible to downgrade the entire navi/hvac console for a standard console bought on ebay (with all the buttons and trims) or the car's harnesses are completely different?

BTW if it's possible, it will be my first Lexus and I would be proud to be on the team!