Motion Raceworks LS 3" OD Overdrive Alternator Pulley - Factory alternators can be very dependable and easy to find, which is why most of the aftermarket industry builds front drive bracketry kits around these pieces. - Designed to be used with LS style 6 rib LS Factory style alternators. Simply remove your factory alternator pulley with a puller and press on this alternator pulley. - Note: This is compatible with LS1, LS2, LS3, LS6, LS7, LS9 alternators. Others may be compatible as well. - Machined from 6061 Aluminum - Made in the USA! - Shims included to adjust pulley for inconsistencies in casting, spacing of factory and aftermarket brackets. - Comes with: 0.019 Shim & 0.039 Shim - Please see the chart for crank pulley size versus alternator pulley speed.