b2000 with 8 bolt crank?

today I went to put the fly wheel from my old b2200 engine on to the new motor, and it had 8 bolts instead of 6? where did it come from? is it stronger than the factory mazda one?

The only aftermarket flywheels I am aware of are Fidanzas and they are direct bolt ups. Someone do and engine swap before u bought truck?bj