identifying flywheel?

hello On leaving my car in to be fixed it was discovered that there was a wrong gear box in it. prior to that the starter had failed twice. it appeared that the former garage who had done work on the car had fitted the starter by breaking off the convex part at the pinion to fit it to the wrong gearbox. there was three of these found in the gear box on removal. the new starter is the right starter on trying to start the car there is trerrible clattering and banging. the starter is ok. its possible the flywheel isthe wrong size it may have been changed to suit gear box. here is the difficulty. how do i identify if its the right flywheel. the car is a fiat bravo 1.2 petrol. the no on the flywheel is 46470371 though this doesnt appear to be the parts no. the fiat parts place told me the proper parts no is 46470360 for my car. they have told me this may be a manufacturers no. but dont know. ive scoured scrapyards for the part to no avail. the part to buy new here in ireland is quite expensive so i dont want to buy it as possibly it might be the same size as the one i already have. How do i find out if the flywheel i have is the right size.