I just bought a Gravely two wheel Pro 12 that came with a 42" finish mower, brush cutter and sickle bar. The mower and brush cutter attach with a spline. The sickle bar has a slip clutch with a "tooth" connection, but no way to attach since it will not connect to the spline on the mower. I am concerned about connecting the brush cutter without a slip clutch. I had a Gravely Pro50 walk behind and currently have a Gravely 60" zero-turn. But the two wheel units are a new venture. Can anyone explain how I can convert to the slip clutch? And suggestions on where to purchase parts?