Raredance: The US Wayfarers that R-J mentions as a quartet later became a trio. There are at least two other albums by the group, "Live at the World's Fair," (that would have been Seattle), and an LP of Civil War Songs.

I only have only of those as a trio and not the same band(s) at all:

Wayfarers
Tom Adams, Dick Bailey, Ray Blouin & Sean Bonniwell ‎– At The World's Fair, RCA ‎– LPM-2946 (see multiple posts above)

Trio#1
Wayfarers
Paul Bain, Lee Schaefer & Ilka Sylvern – 2 LPs for RCA (see: Thomas Stern, 19 Aug 14—09:40 AM, above)

Trio#2
Wayfarers Trio (out of Oklahoma)
Bill Cheatwood, Baxter Taylor III & Mason Williams – 1 LP for Mercury, Songs Of The Blue & Grey, SR-60634, 1961

All three members of the formal "Trio" had a pretty good run in the music biz after they went their separate ways.