I don't think a 92 would have come with a #21 head from the factory. Look on your bellhousing on the passenger side, see if you see a tag like this one:



Casey, even though the car is badged as a 300SD it still has the 3.5l engine

-Jason

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.