Answers, according to "Casino Gaming Token Guide - Lake Tahoe" by Don & Jean (published 1990):

1979 Barneys Lake Tahoe Casino Token = VB (Van Brook Mint)

1981 Sahara Tahoe Token = LM (Letcher Mint)

1983 Del Webb's Sahara Tahoe Token = Not shown in booklet

I don't have these tokens, just the book, so can't tell you where to look for these mint marks.