ok, i have both ecus in front of me. d15z1 ecu is probably one third longer and has 3 grey connectors going into it. #37820-p07-g02 AUU. d16y4 ecu is one third smaller, takes only 2 grey connectors. #37820-p2k-q01 DZ. dont know if this helps. did notice connections to injectors seem different as well as dizzy. oxy sensor and cat are in different places.