I have a 1991 mustang LX notchback. It had the 2.3 in it which I am swapping for a 5.0. The car is a 91. The 302 motor i purchased came out of a 92. The motor comes with the harness. No ECM. Upon my search I keep being asked which one I require and I don’t know if I am supposed to refer to the car for a code or serial number or to the engine the car came from or how exactly I’m supposed to tell the difference between which one I require