I have an excellent quality version of the a capella that I used in my fan mix. It would have been nice to have gotten a little more feedback on it since so many people d/l'd it. Here's 2 of the official a capellas: link link
My mix? Thanks. Glad you liked it.
These are Rick Rubin mixes, but not really. They were available on a vinyl 12" of the WWRY/WATC Ruined Mixes single. These are the closest to the real thing, though.