I recently put together a concert recreating a Mass as it would have been performed in 17th - 18th century France, using one of Couperin's organ Masses. When searching for a Credo, I came across a reference to a 1771 anonymous source from Paris entitled Faux-bourdons pour les fetes solemnelles. While mostly psalm tones were set to 3 or 4 part fauxbourdon, there is one setting of the Credo chant set to 3-part fauxbourdon in this source. I am grateful to have a received a facsimile of the score from the Biblioteque nationale et universitaire in Strasbourg, FR. Here is my transcription and a recording from our concert.
Recorded live, November 16, 2014