Lofat,
Please post whatever results you get if you could. I'm currently having the same problem. Took it to a mechanic with a voltmeter(?) and he said the alt was putting out charge, and the battery was bad. Put a new one in, and about a week and a few days later, it's dead too. Obviously the mechanic didn't know what was up, but I looked at the voltmeter and it seemed like what he was saying was making sense. I wonder if there are any obvious places for a short? I have a new alt. but it looks different from yours. I'm going to try the voltage regulator.
Will

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84 300TD 4 speed, green