04 Cav and a 01 Chevy S-10.Both have the factory stereo's. The S-10 came with the cassette and the Cav came with the CD player. The cassette player is broken and was wondering if the Cav stereo/CD player would fit the S-10? This way I would like to update the Cav with a nicer CD/MP3 set-up. Thanks!

If they are both double din then yes.

the cavalier has serial data coming into it- and the s10 does not, it would fit in there after some crazy bracket changes, but it would be a pain in the ass getting it to work right