ORIGINAL: foxys
Are you sure it's the flywheel and not the spur gear? The flywheel doesn't have any teeth, and the spur gear is likely plastic, and just as likely has broken some teeth, this is a fairly common thing with the plastic spur gear. If it's the spur gear, replace with a MPO-017, 43tooth steel spur gear and you won't break it easily.
Great idea and no you wont have any problems at all replacing the spur gear. losen your engine screws at the bottom of the engine so that your engine will move to the side. You will probably have to remove the center diff which is what your spur gear is on and replace make sure when you put your center diff back in the truck and you tighten your engine back down you place a bussines card in between the cluth bell teeth and the spur gear teeth you can have the right mesh set up and that the car rolls freely when you push it without any binding.