This came out of a dollar bin in Chicago last weekend. I had always heard the weirdly mixed vocal version of Secret Weapon's 'Must Be The Music' of their self titled and only (I think) album, but picked up a 12" with an instrumental mix on the flip when I saw it as the vocal is what always slightly turned me off the original. Result, they replaced the male sung passages with maybe the greatest guitar solo in funk history:

Secret Weapon - Must Be The Music (Instrumental)