not sure about the legality of engines built by hm 5 star and rpm engines as i notice the one i had in my hz was an engine number from a hq, but no problems when i informed vicroads of the changed engine no. Also i have noticed my ute has an rpm engine in it which has a QR engine no. again which is wrong for a wb, but no problem when i informed vicroads of the engine no change, even though the previous owner never informed them and the engine has been in it for 10 years, but both had the correct pollution gear for the time of the vehicle.