I read back through this thread and noticed there hasn't been any mention of checking all of the grounds for this problem. In particular, the engine-to-chassis ground strap. If this strap is corroded/loose, it can cause very intermittent problems. This could also be the reason the alternator keeps failing. Also, check the grounding of the voltage regulator to the alternator casing.

I've encountered both of these problems and scratched my head for a bit, trying to resolve a no-charge problem.

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Sam

84 300SD 350K+ miles ( Blue Belle )