If I'm guessing right, Tommy Mooney saw a group in which Eric Weissberg played QUITE A FEW YEARS BACK....."New Purple South" is a fun guess, but they were called the Blue Velvet Band. Absolutely legendary, they made one album, which cannot be found anywhere, with Richard Greene playing fiddle and Weissberg playing steel guitar. I still do one of the songs from that album, called "Hitch-hiker"- a wonderful progression, and a real crowd pleaser. Sorry, can't help you on the Greenbriar Boys albums.