Don't you hate it when they reuse model numbers like that? I remember a comic conversation with a JD parts guy when the '420' lawn & garden tractor came out - he kept insisting that the part in his hand was correct, and I kept saying no, not the L&G tractor the older 420 crawler!

Anyway, onto the serial numbers for the JD400G crawler.
1988 742614 - 747920
1989 747921 - 764403
1990 763404 - 771695
1991 771696 - 778725
1992 778726 - 787254
1993 787255 - 795279
1994 795280 - ?
This was made from 88-97, but the list I have only goes up to 1994.
The source of the data is from a farm equipment quick reference guide that's intended to assist dealers in determining the year and current market value of trade-in equipment.
The guide as such only lists the beginning serial number for each year. I'm making the reasonable presumption that the last serial number for any given year is one less than the starting serial number for the successive year.
Thanks to Digitup for sharing the relevent pages from his guide with us so we can determine what year a given machine is.
Stan