If it checked out okay this is wiring. New ends, dielectric silicone on the connections, check that wiring is sound into the jacket down there.

You might want a second opinion on the alt. I know you get a better look from better eyes at a small shop; any brightly lit retailer is compensating for low internal lighting conditions if you know what I mean.

When I had my alt done at P&R Starter and Alternator in Hagersville (they are great) I *SAW* all 3 diodes working on their scope. They just put in new brushes and I reinstalled. Cheap too :)

Also confirm belt tension. I really leaned on it when I put it back in.

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Stef -- 1981 wagon B21A SU M46 317000km