Overview SD-8 Alternator The spline-driven SD-8 alternator offers the benefits of an exceptionally lightweight alternator, and a design with proven durability in the rugged world of aerobatic aircraft. Weighing just 2.9 lbs., with a rated output of 8.4 amps @ 3500 alternator RPM, the SD-8 may be mounted on either the vacuum pump accessory pad, or on the hydraulic pump pad. It features a strong billet aluminum mounting flange, sealed ball-bearings, and a special "shear section" in the drive coupling. Shipped with a matching regulator. For Experimental Aircraft ONLY