Would be hard to find, and expensive when you do. It's probably just a dimensional difference, probably height, or it might have something welded onto a tooth. It'll just be something to make 1 tooth stand out so the sensor can count revs.

I modify flywheels to run with gearbox mounted speed sensors all day long, we just spot weld some flat welding wire onto a tooth. At the end of the day its just some metal passing over a magnet making a current. Same as an alternator or dynamo or generator.