You can find an older shaft style radio if you don't want to cut the dash. Some of the late 80s early 90s were pretty decent before they changed over to the din style, I had a pioneer that had preouts and a jvc that had cd changer controls.
http://cgi.ebay.com/ebaymotors/PIONE...fAudioQ5fVideo
For the 94 the radio will get mounted in the center of the dash with a kit like this.
http://cgi.ebay.com/Chevy-GMC-Pickup...item5d2ecf590f