Excuse the question that I'm sure has been asked many times before but...is the Isley Brothers' version of I Heard it through the Grapevine available anywhere? I looked for it years ago and it was apparently still elusive, has anything changed?

I have also heard theories that the song was never recorded [[there was an intention to do with the IBs but it fell through); this seems plausible as I can't imagine how something like this could have remained unreleased for half a century.

On a similar note, who else at Motown performed I Heard it through the Grapevine? I know of the Miracles, The Pips and Marvin of course.