Well, this Crystal recording on YouTube says it comes from 1975.
https://www.youtube.com/watch?v=oM2uAnW2LU0
Is this Buckingham Nicks as it says? I don't think it's Fleetwood Mac, but then again the video says the recording is from 1975. Maybe Lindsey and Stevie played a side gig in Arizona?
The harmony work here sounds fantastic. Really, there's no reason why this song never has re-emerged in a live setting for Stevie and Lindsey together, or Angel or I Don't Want to Know. If they ever felt like playing up the duo dynamic, these songs definitely would do it!