Good question and I am in the same boat with a 1994 D90 insured with Geico. Might be worth the change to a carrier that uses a different source other than KBB.
1994 Defender 90
2006 LR3 SE
1996 Discovery I (sold)
1991 Range Rover Classic (sold)
1995 Range Rover Classic (sold)
2006 LR3 SE (sold)