cdiiwu

hey guys im looking to buy a Grom Audio usb adapter so i can play music from my iphone in my car, but I just want to make sure I order the right one. Before I order one, does anybody know if the cd players on the toyota aristo and lexus gs are exactly identical?...I dont wanna order the one for the gs300 and not be able to even use it in my aristo. Also, mine is the one with navigation and a '99(if that makes any difference)