Leave it to MSD to build an all-out performance distributor to replace the OEM GM LT1 Optispark! We machine an entire billet block of aluminum down into a precise housing that fits in place of the factory piece. Then, we fill it with a reliable new pick-up assembly, a trick timing adjustment mechanism and top it off with an all new MSD distributor cap! The pick-up is an advanced optical encoder, a different style of optical pickup than the OEM. This type of pick-up has proven to be very reliable and stable through extreme rpm and conditions. The rotor is bolted to a drive assembly that is indexed to the shaft and is stabilized through the use of a large ball bearing assembly. Once installed, you have the ability to adjust the ignition timing the only distributor that offers timing adjustability! An adjustment screw allows the timing to be tweaked up to +/-5. The distributor is equipped with a fresh air vent and has an extra thick mounting surface for the cap to eliminate leaks. The distributor is supplied complete with our heavy duty LT1 Cap, Rotor and the components required for installation. MSD Pro-Billet GM LT-1 Distributor 83811 Includes Cap/Rotor/Components For InstallationAdvanced Optical Encoder Trigger DesignDesigned For Accuracy And ReliabilityEasily Adjust The Timing Up To +/- 6 DegreesImproved Housing Design Eliminates LeaksSupplied w/Heavy Duty LT1 Cap And RotorSealed To Keep The Elements OutLarge Ball Bearing Stabilized TimingRotor Drive Is Positively Indexed For No-LippingPit Stop USAoffers MSD Ignition Pro-Billet GM LT-1 Distributor 83811 at low everyday prices. Be sure to check out all of the products from MSD Ignition including MSD Ignition Parts and Accessories, MSD Distributors, MSD Chevrolet / GM Distributors, MSD Chevrolet / GM Distributors.