Alternator is no good. The two they have gotten for me so far are no good as well, according to their test machine. Is this a common problem? I didn't expect to fight with this for an entire weekend. Losing my patience

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1982 300d -Adolf- Got it for 500 bucks from a guy that thought he knew how to make biodiesel. Even the best diesels won't run on burnt french fry ends! 318,000 and counting
1982 300cd -Erwin- 107,000 miles! The most fun you can have in a diesel. Wrecked by an idiot, massive insurance payout for me. Tough to see you go, my friend.
1983 300d -Katrina- Another five hundred bucks. Straight outta New Orleans, by way of Maryland. Work in progress. 291,000 and counting