luvmy99GS400

Hello, I have been shopping for a replacement CD player to go with the nav unit in my '99 GS400. If it say Nakamichi CD player, but it looks the same as the glove box unit i have currently will this work even if the Nav is not Nakamichi? Also some of the things i have read say you need to go to the dealer to get it to work or recognize it if you replace it. Is that true or can I just swap them out? I would rather get something that could connect to an IPOD, but since i have a tape deck instead of an AUX button I guess I'm screwed unless i want to replace all the climate controls... any suggestions on this one too? thanks everyone in advance for the help. Cheers,