Originally, the GM HEI Distributor was a good economical plan with everything in one housing and easy installation. However, when it came to performance, it fell far short. That is why MSD engineers designed a Pro-Billet HEI Distributor along with a powerful ignition module and coil.
Drawing on years of high performance ignition experience, MSD engineers created a unique digital ignition module and internal coil that are capable of running above 9,000 rpm. Stock and other "performance" modules lose spark energy at about 4,500 rpm. The MSD module produces 50% more current than stock units and delivers a much more precise timing signal as well as dwell control. This module also has a built-in rev limiter!
For strength and high rpm stability, the QPQ treated oversized shaft is guided by a sealed ball bearing and long sintered bushing. The QPQ coating provides a low friction coating on the shaft and also makes it highly resistant to corrosion.
Tig welded to the top of the shaft is MSD's adjustable mechanical advance assembly. The distributor is supplied with extra springs and stop bushings so you can tailor an ignition curve to match your driving needs. The advance assembly features chrome moly weights that slide on nylon pads for smooth, timing advancement through the entire rpm range. There is also a vacuum advance canister to improve economy while cruising.
All of these features are enclosed in a great looking, billet aluminum housing that is CNC machined for accuracy and incredible strength. The distributor comes complete and ready to drop in with a high quality rotor and cap with brass terminals for great spark transfer. Simply connect a 12 volt source to the distributor and you're up and running.

NOTE: The PN 8365 is designed to replace GM HEI Distributors that use a 4-Pin ignition module.