hello first time here have an active jtd 2005 with350,000 miles need to change flywheel got one from fiat wont fit done this 3 times back and forth, car in garage any ideas

might seem obvious but is there a part number on old flywheel?

Also, try taking the old flywheel to the motor factor so that when they get the replacement flywheel out you can compare the two on the counter.