Stealth 316 - 3000GT/Stealth Stereo Connectors
See also
Stealth 316 - Sony CDX-M800 Head Unit Installation
Scroll down for a nice view of what the wires should have on them.
Make sure you have +12V on the right connector. If you have a separate CD/cassette there is a plug into each one. Should you want to put in an aftermarket there's a nice adapter so you don't have to hack the harness.
Stereo Harness Adapter 3000GT/Stealth*-*Mitsubishi 3000GT*/*Dodge Stealth