Jamesis300

i have an 01 is300 automatic building for wife got it dirt cheap guy took the motor out of car and broke stuff and cut things so I got a 02 motor but the 02 wire harness won't plug in to the 01 ecu do I need the 02 ecu or do I just change the 02 motor harness to the 01 harness thanks and if I'm in the wrong place I'm sorry new here and I've done a lot of looking