Whats up AFM...I'm new to the forums as well as the foxbody mustangs, always loved them. Recently purchased a 1989 4 banger (5spd), possibly bad head....my question to the forum is this... could a replacement 2.3 (8 plugs) from an 93 (auto) work with my '89 (5spd) setup that had the 2.3(4 plugs) or would I have to change the ECU as well?