my '83 300D is totally stock . . . nothing but original (except for a few replacement parts here and there, but basically OEM setup). What is available the fuel department?

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1983 300D, the "Avocado"
1976 240D, 4-spd the "Pumpkin", SOLD to Pierre
1984 190D, 2.2L, 5-spd, my intro to MBZ diesels, crashed into in 2002