Here is a link to 04 Alero brochure:
http://www.outrightolds.com/images/pdfs/alero2004.pdf
GX 6 speaker standard
GL1, 2 and GLS 6 speaker CD with RDS and speed compensating volume standard.
Available XM and 8 speaker CD and cassette, RDS and speed compensating volume. GX-GLS models.
Pat