Hi Dregg,
I don't see CBZ identified in the Standard Catalog.
My 642LS is CBU, though, and it shipped in March 1997. There are several CB serial numbers from 1997 through 1999 so somewhere in there would be my guess for your gal's LS.
Here's mine. I do have the original style rosewood grips, but these Altamonts just feel better.