WOW!! I was right on the spacer.
Thanks for the year model. That spring was on the following models:
Model (18):
KDX200-H1 (KDX200) (1995)
KDX200-H10 (KDX200) (2004)
KDX200-H2 (KDX200) (1996)
KDX200-H3 (KDX200) (1997)
KDX200-H4 (KDX200) (1998)
KDX200-H5 (KDX200) (1999)
KDX200-H6 (KDX200) (2000)
KDX200-H7 (KDX200) (2001)
KDX200-H8 (KDX200) (2002)
KDX200-H9 (KDX200) (2003)
KDX220-A10 (KDX220R) (2003)
KDX220-A11 (KDX220R) (2004)
KDX220-A4 (KDX220R) (1997)
KDX220-A5 (KDX220R) (1998)
KDX220-A6 (KDX220R) (1999)
KDX220-A7 (KDX220R) (2000)
KDX220-A8 (KDX220R) (2001)
KDX220-A9 (KDX220R) (2002)
The spacer I referred to was on:
Model (58):
KDX200-E1 (KDX200) (1989)
KDX200-E2 (KDX200) (1990)
KDX200-E3 (KDX200) (1991)
KDX200-E4 (KDX200) (1992)
KDX200-E5 (KDX200) (1993)
KDX200-E6 (KDX200) (1994)
KDX250-D1 (KDX250) (1991)
KDX250-D2 (KDX250) (1992)
KDX250-D3 (KDX250) (1993)
KDX250-D4 (KDX250) (1994)
KX125-E2 (KX125) (1987)
KX125-F1 (KX125) (1988)
KX125-G1 (KX125) (1989)
KX125-H1 (KX125) (1990)
KX125-H2 (KX125) (1991)
KX125-J1 (KX125) (1992)
KX125-J2 (KX125) (1993)
KX125-K1 (KX125) (1994)
KX125-K2 (KX125) (1995)
KX125-K3 (KX125) (1996)
KX125-K4 (KX125) (1997)
KX125-K5 (KX125) (1998)
KX125-L1 (KX125) (1999)
KX125-L2 (KX125) (2000)
KX250-E1 (KX250) (1987)
KX250-F1 (KX250) (1988)
KX250-G1 (KX250) (1989)
KX250-H1 (KX250) (1990)
KX250-H2 (KX250) (1991)
KX250-J1 (KX250) (1992)
KX250-J2 (KX250) (1993)
KX250-K1 (KX250) (1994)
KX250-K2 (KX250) (1995)
KX250-K3 (KX250) (1996)
KX250-K4 (KX250) (1997)
KX250-K5 (KX250) (1998)
KX250-L1 (KX250) (1999)
KX250-L2 (KX250) (2000)
KX500-C1 (KX500) (1987)
KX500-D1 (KX500) (1988)
KX500-E1 (KX500) (1989)
KX500-E10 (KX500) (1998)
KX500-E11 (KX500) (1999)
KX500-E12 (KX500) (2000)
KX500-E13 (KX500) (2001)
KX500-E14 (KX500) (2002)
KX500-E15 (KX500) (2003)
KX500-E16 (KX500) (2004)
KX500-E2 (KX500) (1990)
KX500-E3 (KX500) (1991)
KX500-E4 (KX500) (1992)
KX500-E5 (KX500) (1993)
KX500-E6 (KX500) (1994)
KX500-E7 (KX500) (1995)
KX500-E8 (KX500) (1996)
KX500-E9 (KX500) (1997)
KXF250-A1 (Tecate 4) (1987)
KXF250-A2 (Tecate 4) (1988)
I think I remember having to put an adapter on someone's 1995+ shock years ago when I swapped their 5.0 for one from a KDX250.
Maybe you can find an adapter on eBay. I don't have any handy.