Yeah, I'm sure macfan57 is right, it's never been on a legit CD that I know of.
As for compilations albums it may be on, I'm not sure of any others but it is on this one:
http://www.fleetwoodmac.net/penguin/albums/bestoffm.htm
...as this is the one I have in my collection that represents this track. I've been hashing around the idea of getting the Dragonfly/Purple dancer single for my collection instead but this album also has the original single mix of "World in harmony" as well so I'm hanging on to this album until these two tracks (in the way in which they are presented on this album) get released on CD.
John