Both were great musicians. The The Ballad of Jed Clampett on TV is played by them but not sung by them. However they do sing it on albums. Another guy Jerry Scoggins sang it for TV. The writter of the series Paul Henning wrote the song.
There is a great video on You Tube with Earl Scruggs, Randy Scruggs, Chet Atkins, Daune Eddy, Vince Gill, and others all playing Lonesome River.
I liked the show when Cousin Roy (Roy Clark) would show up too.
Here is a thread http://www.freerepublic.com/focus/f-news/1297876/posts from 2004 when Jerry Scoggins died.