Clean your sending unit. It comes out of the tank by removing the first aid kit. Once you get it removed, it comes apart easily and you will find that it is full of gunk that keeps the float from going all the way to the bottom. You can even clean the contact for the low fuel light while you are in there and perhaps get that working again.
Its easy and satisfying, just be careful to not break the wires.

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1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660