Will a turbo engine not fit your 1978? Seems you could get a good turbo OM617 for <$500 and turbo is a great fit for diesel (more power w/ no efficiency loss). Downside is that NA are more reliable and less risk of being damaged if you must risk buying w/o testing it first. I wouldn't pay over $200 for an engine that has been left outside in the rain & snow. Water could have gone down the air cleaner into the cylinders. At least insure you can turn over the crank.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans