Thank you. I think that answered my question. The MSD 8350 is self contained and does not rely on the external MSD 6AL box. It is the MSD 8577 distributor combined with the 6AL (or newer) box that needs the adapter. The Progression unit likely triggers the tach wire in the same way as the stock Ford distributor. Thus, the Progression distributor does not need a tach adapter as far as I can tell.
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