Becker who make the OEM manuals have listed all Porsche Radio/Audio Manuals for download on this below link
http://www.beckerautosound.com/Porsche/Porsche Menu.html
Year Type Radio CD Changer
1996 Carrera CR210 Cassette (2162) CDC3
1996 Carrera CDR210 CD (2262) CDC3
1997-98 Carrera CR210 Cassette (2182) CDC3
1997-98 Carrera CDR210 CD (2262) CDC3
1999-01 Carrera/Boxster CR220 Cassette (4362) CDC3
1999-01 Carrera/Boxster CDR220 CD (4462) CDC3
2002 Carrera/Boxster CR220 Cassette (6624) CDC3
2002 Carrera/Boxster CDR220 CD (6625) CDC3
2003-04 Carrera/Boxster CDR23 (6611-6612) CDC4
2003-04 Carrera/Boxster PCM-2 (6633-6634) CDC4
2003-04 Cayenne CDR23 (6627) CDC4
2003-04 Cayenne PCM-2 (6636) CDC4
2005 Carrera/Boxster CDR24 (6645) CDC4
2005 Carrera/Boxster PCM-2.1 (6644-6642) CDC4
2005 Carrera / Boxster Navi Drive (6648)
http://www.beckerautosound.com/Porsche/Porsche Menu.html
Year Type Radio CD Changer
1996 Carrera CR210 Cassette (2162) CDC3
1996 Carrera CDR210 CD (2262) CDC3
1997-98 Carrera CR210 Cassette (2182) CDC3
1997-98 Carrera CDR210 CD (2262) CDC3
1999-01 Carrera/Boxster CR220 Cassette (4362) CDC3
1999-01 Carrera/Boxster CDR220 CD (4462) CDC3
2002 Carrera/Boxster CR220 Cassette (6624) CDC3
2002 Carrera/Boxster CDR220 CD (6625) CDC3
2003-04 Carrera/Boxster CDR23 (6611-6612) CDC4
2003-04 Carrera/Boxster PCM-2 (6633-6634) CDC4
2003-04 Cayenne CDR23 (6627) CDC4
2003-04 Cayenne PCM-2 (6636) CDC4
2005 Carrera/Boxster CDR24 (6645) CDC4
2005 Carrera/Boxster PCM-2.1 (6644-6642) CDC4
2005 Carrera / Boxster Navi Drive (6648)