Definition of the Vintage B.C.Rich at this web site.

Hand made in U.S.A, Neck thru.
Only Seagull,Eagle,Mockingbird,Bich and Worlock. Also Ultra Rare other models.
Serial Number is from 5 digit 76000 to 88XXX, and 6 digit 75XXXX. There are some PROTO or BICH XX.
Must have original electronics circuits. The most populer type is full electronics circuits that include booster, phase switch, coil tap and varitone switch. However there are some passive models.
Koa , Maple and Mahogany wood. Rerely, there are Walnuts , Brazilian Rosewood .