I have a PerTronix kit for that one. No external box is needed. It requires a standard ignition coil and a 2 wire hook up. It screws in in place of the points. The magnet is made for the breaker cam, so you don't have to align anything. No "erector set" bracketry inside the distributor. Same price as the Crane stuff,30 month warranty.
Sorry to take the space here. But I used to use optical systems back in the early eighties. There is a better way. Contact me privately for details. WDurrance@aol.com
Randy D.

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W.R.Durrance
ASE Master Tech
Mercedes Tech 21 Years
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W.R.Durrance Engineering