I believe on the 05 G35C the radios play MP3 cds. Does anyone know if the 04s do too? and also, if they dont, is do the 05s fit in the 04 dash

 

No, the '04's do not have this capability. Not sure about your 2nd question. However, I am quite sure someone else will have an answer for you.

 

the answer to both your questions are no i believe.

 

anyone know the differences of the radio setup for both years?

 

The 04 does not play MP3, and the 05 WILL fit into the 04 with slight modification. User ACCORDFREAK has attempted this.

 

talk about a BUMP! 2 1/2 yrs

 

I saw it so I figured I would awnser it regardless, lol. Have you installed the 05?

 

no, just did the Ipod Interface instead

 

Which one did you install? I am thinking about doing the 05 swap. I really want to play Mp3's

 

If you have an Ipod, just do the interface. I forget the model num. There are write ups for it.
http://cgi.ebay.com/USA-Spec-iPod-interface-for-Infiniti-PA11-NIS-1999-2006_W0QQitemZ220212281635QQihZ012QQcategoryZ48680QQrdZ1QQssPageNameZWD1VQQcmdZViewItemfound item on ebay