I again disassembled them, wire brushed the steel parts to bare metal, and shot each component, including the weights (which had been rusted solid on the shaft) with a light coat of epoxy PPG primer that I was using for something else at the time.

I had some 2 part Sharkhide (brand) acid cleaner and sealer that I also had laying around that I used for the the aluminum distributor body as it also had badly corroded, then I assembled with new magnetic pickup, rotor, and the correct marine distributor cap that does NOT have the small black vent cap on top like the regular automotive ones have (coast guard regs.... no vent/spark hazard from a vented cap).

I also sprayed inside a very light mist of Gibbs Spray on everything including the reluctors and pickups before closing it up

I just took dizzy's out a couple weeks ago after running them again for about 8 months to redo some intake gaskets and this is how they still look.... I was kinda shocked as there is minimal corrosion after doing these simple mods. (the rough aluminum look is from the previous corrosion).

My theory, at least on a marine application, even though there is no water or spray mist getting in the bilges, when the hot engines are shut off after a day of use.... including running them with fresh water for 15 minutes to flush, as the distributors cool off they are sucking humid air in as they cool down, which is causing the massive rusting problems.

I think that by this coating of all the inside components (there is minimal or no coating from MSD on these components whatsover) and possibly by NOT using the vented type caps (some air does still come in through cap edges i am sure) I think I found a solution of the corrosion/rusting that most ALL marine MSD users face......

I originally did a search how to combat this, and found TONS of automotive users were complaining of the same rusting issues on their MSD's