Hmmm, I will call Saber to verify but I received my prop and saber spacer from Catto. Catto also drilled my spinner holes and made my cutouts. I received no optional spacer with my order.
The DWG C4 says optional spacer (.125 2024-t-3), prop and spacer thickness should add up to 4 3/8 inch. My Catto hub measures 4 3/8 inches without the optional spacer. My spinner holes lined up great as delivered from Catto without the optional spacer so I assumed I don't need it. I will call on Mon to double check and can post on that call if you like.
Dbro172, do you have your prop and extension already?