I think these are all correct.
Interchangeability is according to the book
Year Model Engine ID# Engine case interchange
1974 KX250 K2E 900001 - K2E 903675 FITS 74-79 KX250
1975 KX250 K2E903676 - K2E907900 FITS 74-79 KX250
1976 KX250 K2E907901 FITS 74-79 KX250
1976 1/2 KX250 KX250AE0018 FITS 74-79 KX250
1977 KX250 KX250AE0018 FITS 74-79 KX250
1978 KX250 KX250AE 000001 FITS 74-79 KX250
1979 KX250 KX250AE001801 FITS 74-79 KX250
1980 KX250 KX250AE0056 FITS 80-81 KX250
1981 KX250 KX250AE0082 FITS 80-81 KX250
1982 KX250 KX250AE010801 FITS 81-82 KDX250 1982 KX250
1983 KX250 KH1 KX250CE000001 FITS 83-84 KX250
1984 KX250 KH1 KX250CE002801 FITS 83-84 KX250
1985 KX250 KX250DEXXXXX FITS 85 ONLY
1986 KX250 KX250DEXXXXX FITS 86 ONLY
1987 KX250 KX250EE00XXXX FITS 87 ONLY
1988 KX250 KX250EE00XXXX FITS 88 ONLY
1989 KX250 KX250EE01XXXX FITS 89 ONLY
1990 KX250 KX250HE00XXXX FITS 90 KX250 ONLY
1991 KX250 KX250HE00XXXX FITS 91 KX250 ONLY
1992 KX250 KX250JE00XXXX FITS 92 KX250 ONLY
1993 KX250 KX250JE00XXXX FITS 93 KX250 ONLY
1994 KX250 KX250KE00XXXX FITS 94 KX250 ONLY
1995 KX250 KX250KE00XXXX FITS 95 KX250 ONLY
1996 KX250 KX250KE00XXXX FITS 96 KX250 ONLY
1997 KX250 KX250KE01XXXX FITS 97 KX250 ONLY
1998 KX250 KX250KE02XXXX FITS 98-99 KX250 ONLY
1999 KX250 KX250LE00XXXX FITS 98-99 KX250 ONLY
2000 KX250 KX250LE01XXXX FITS 2000 KX250 ONLY
2001 KX250 KX250LE01XXXX FITS 2001 KX250 ONLY
2002 KX250 KX250LE06XXXX FITS 2002 KX250 ONLY
2003 KX250 KX250ME00XXXX FITS 2003 KX250 ONLY
2004 KX250 KX250ME00XXXX FITS 2004 KX250 ONLY
2005 KX250 KX250RE00XXXX FITS 2005 KX250 ONLY
2006 KX250 KX250RE00XXXX FITS 06-07 KX250
2007 KX250 KX250RE00XXXX FITS 06-07 KX250