Pharoah Sanders - Black Unity
Black Unity is one song played live that lasts about 35 minutes and it's free jazz but it has a very deep groove. There's a drummer and a couple of percussionists and the bass player is locked into them. It's almost the jazz version of the Stooges song 'Fun House' if that makes any sense.

It's not free in the sense that the drummer's going off, or everyone is going off at once. There's a deep groove but there's also looseness to it too.