Moser Pro Spools are offered in 40 spline for 9” Ford applications in both aluminum. Spool is made with oversized bearing areas and must be used with the 3.812” bore aluminum case. Our Moser Pro Aluminum Spool features a thicker ring gear flange for increased strength and weighs only 5.4 lbs.!Application: 9" Ford 40 spline (8.5 lbs)