If you use an MSD ready to run distributor, you can use vacuum advance or not and the unit is packaged with different advance springs, so you taylor your advance curve. HEI is nice if you have the clearance, but sometimes in an effort to save a little coin you may make changes to your precious truck that you wish you hadn't (such as taking a hammer to the firewall).

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87 GN, and new toy: 1955 Chevy 3200 pickup, soon to have: 383, Cola crank, Childs/Albert 6 inch rods, Brownfield heads, 10:1 KB hypers, CompCam 284 Extreme Energy, Tilton Plate transmission realignment and built Turbo400.