This is our most popular performance distributor! The housing is machined from a billet of 6061-T6 aluminum on a state-of-the-art CNC machine producing exact tolerances. For high rpm stability, a . 500" steel shaft is supported by a sealed ball bearing and a long sintered bushing. This shaft also receives a QPQ coating for friction reduction and resistance to corrosion. a precision machined reluctor is attached to the shaft which triggers the magnetic pick-up mounted in the housing. This high output magnetic pick-up is the most accurate way to trigger your ignition. Plus, with no moving parts to wear or adjust, the pick-up is maintenancefree! Just above the pick-up is MSD's adjustable mechanical advance assembly. Different springs and stop bushings are supplied so you can tune an advance curve to match your application. Features: CNC machined billet aluminum housing and billet aluminum baseEasy-to-adjust mechanical advance with supplied springs and stop bushingsMaintenance-free magnetic pickup and precision reluctor create stable trigger signals throughout the rpm rangePolished steel shaft is QPQ coated and guided by a sealed ball bearing and extra long sintered bushingAdvance plate and weights are fine blanked from chrome moly steel and QPQ coated for friction reductionMechanical advance assembly can be locked out for crank trigger systemsAdvance weight pins are staked and tig welded to the plateNylon pads ensure smooth operation of the advance weightsSpecial oil tract improves lubrication to the distributor and cam gearO-ring seals can be added to modified blocks to improve oil pressure controlSupplied with an HEI style distributor cap and rotor (accepts Cap-A-Dapts)Must be used with an MSD Ignition ControlWill not accept a vacuum advance canisterNo CARB Exemption Order NumberPit Stop USA offers MSD Pro-Billet Distributor - Chevy V8 85551 at low everyday prices. Be sure to check out all of our products from MSD including MSD GM Distributors.