TD has the large (46mm?) socket on the sender unit for fuel tank accessible thru the rear floorboard. Large channel locks won't work because it is set into a recess. I looked for a large socket but none at hardware store or auto parts store. So I used a large adjustable plumbing wrench called a lock/adjust wrench designed for big nuts on toilet tanks. They're available at most hardware stores and the jaws are thin enough to get into the recess. Just set it at the appropriate width, lock it in place and put the wrench straight down vertically on the flats of the sender hex nut. I then put a 16" 1/4" extension thru the hole at the end of the wrench handle and used it to turn the wrench. Sender loosened easily.

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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