Hey there. Welcome to the club! Good to see another person in Adelaide!
Tell you what though - we will only give you information if you promise to come along to the next cruise (assuming the car is drivable

).
Just kidding.....
You didn't say if it is an auto or manual? I am going to assume an auto. You could find someone who specialises in Mitsi's, as the tip gearbox is very similar, if not the same, as the one in the Magna. I am sure I will get corrected if that is completely wrong.
If it is a manual, then anywhere really.
You could give Graham West Automotive (not sure about the automotive bit) a call and see who they recommend. Apparently, those guys are excellent to deal with. Luca has had good things to say about them too.
Best of luck! BTW - tell us more about your car. Where abouts in Adelaide are you?