WZ wrestled with this song for ages, but was never happy with the feel. The alt. version above is one of those.
When Mick Fleetwood and John McVie had a go, it all fell into place and the rest is history. It's gloriously wonky, and hard to replicate.
FWIW, I'm not a fan of the alt. version. It sounds half-baked, and to be fair, probably was.