I recently put the pencil type plugs in my 77 300d and cold weather starting is GREATLY improved. I couldn't figure out why the 85's started so much better until I did the switch. Now there is no difference between them. The pencil type plugs added at least another 10 degrees to the lowest temperature at which the vehicle would start, perhaps even 15 degrees.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13