Never seen a Chevy LS V-8 in a 300D, but it would be neat. People would comment on how quiet your diesel idles. But, any such redesign is extremely complicated, with many "can't get there from here" issues. Biggest would be getting an oil pan that would clear the K-frame. I haven't seen any U.S. engines with a front sump, as you would need. Must also clear the steering linkage and such.

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