I put my headunit that was in my winter car into the mustang because I got sick of it not playing cd's sometimes. Something I found out was if you buy a headunit that has front, rear, and subwoofer outputs theres a piece that has 4 rca's on it and the other side plugs into your factory harness. It's alot cheaper that that adapter piece with the gain controls on it and the SQ is tons better. This is what it looks like