The date your VX left the lot. Although the actual production date would be better. IIRC you may have a sticker on the underside of your center console lid that lists the month and year of manufacture. If the compressors were changed mid-year knowing your production date might give us a better idea of when the change was made.
Apr 13 2000
my guess is the 99 and 00 models had the KDV-14D and the 01 models had the KDV14G but i could def be wrong about that