Bill Monroe and Lester Flatt. The Blue Grass Boys and the Nashville Grass. They’re all together on stage at the Grand Ole Opry, and the harmonies are so perfect you’d swear it was 1946 again. The song is “Will You Be Loving Another Man?” Lester Flatt, the consummate M.C., fills in the rest of the details.

I don’t know who’s on bass. Other than that, here’s the lineup:

Fiddles - Paul Warren, Kenny Baker, Joe Stuart, Joe Edwards
Banjo - Jack Hicks
Mandolin - Bill Monroe and Roland White
Guitar - Lester Flatt and James Monroe