1974 Brain Box saves the day.

George Jets said
After a second look at what is left of the case and the epoxy, looks like there may be a whole other secondary board down in all that epoxy. Don't know how I would get that out without total distruction..

I do have a photo of the back of my '74 module that melted most of that out from the hot Florida Sun as a clue to what is in there.

This one from '74 looks really nasty, though it performs perfectly yet. That's the way i like to see them built. Coming in half shot up and still working like a charm.

Blue 4 pin below:
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'74 heat ravaged module below:
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Mopar Original '74
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This looks like an exact copy of the board inside the crusty '74 module. This one looks like a single board setup as you can see the plug soldering for going out fhe top side. This is a good style that I would like to copy and remake, has the good T03 External transistor too.

Look at those bottom side "Dual" heat sink tabs. Maybe that is one reason this '74 model is so tuff. They protrude out beyond the epoxy filler to cool to the atmosphere.

Have seem some others with one back side heat sink tab, and most with none just sealed with epoxy.