MW Aluminum through bolt case (3.812" bore), aluminum caps, lightweight steel spool (40-spline), 1/2" ring gear bolts, MW 35-spline 1350 series pinion yoke, ball / taper bearing pinion support, and large pinion 9310 pro gear. All MW Thirdmembers include shipping / storage transporter and 3 quarts of gear lube. (62 lbs) Installation - Service instructions can be found on Service Bulletin #0038.