mickey tee, and 'H', the 'twin cam 16' refers to the fact that the car has 2 cams and 16 valves... 4 per cylinder. the st183 is the code for the convertible version of the st184 we commonly see in oz, and i'm almost certain that that model only came out with a 2.2L 5SFE in oz (the 3sge (2nd generation) was avail in other parts of the world), but now that i think about it, i'm not 100% sure that the convertible was avail in oz to begin with (i'm not old enough to remember). look on the VIN and engine no's for either 5S or 3S and you'll have your answer as to the engine type if you post a pic, it'll be easy as to tell