tienzien

ok so i have a 98 ex obd2a motor which i crashed and my friend have a 99 shell (obd2b) laying around so he gave it so i can put in my old motor just to get me on my feet. i have a question about how should i set up my ecu, since im reusing my obd2a engine harness, should i use my obd2a ecu or should i be using the one in the shell obd2b ecu.